Hours before the biggest moment of his career, the 20-year-old goalie with the patience and cool of a grizzled veteran smiled when he heard the news. It was a slow grin that revealed a glow of confident readiness. Not smug, not a smirk. Just ready.

It was the morning of Game 4 of the Stanley Cup Final and Andrei Vasilevskiy had learned that he would be starting against the Chicago Blackhawks in place of the injured Ben Bishop. Four days earlier, he hadn’t had time to smile or savor a moment that was as meaningful as the one the previous December when he beat Philadelphia 3–1 in his NHL debut. In Game 2 of the Final, he’d suddenly been sent in—twice—during the third period to protect a one-goal lead in what became a historic relief outing.

For Vasilevskiy, who turned 21 on July 25, staying ready on hockey’s biggest stages is the name of his game. According to those who have played with and coached him at his three professional stops in the KHL, AHL and Tampa Bay, being ready for huge moments has been the story of his life.

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The son of a goaltender, Vasilevskiy came of age in his native Russia as a junior league backup for Tolpar UFA who routinely stepped into the international spotlight and shined. He impressed in six World Junior Championship appearances, beginning at age 15. As a 17-year-old he played in the 2012 U18 and U20 WJC tournaments, appearing in 10 games. Sharing netminding duties with Andrei Makarov on the U20 squad, he went 4-1 with two shutouts, a 2.01 goals-against average and .953 save percentage while helping Russia win the silver medal.

“The world juniors is usually a 19-year-old tournament,” says NBC analyst Pierre McGuire, who was rinkside for Game 2 and Game 4 of the Cup Final and has followed Vasilevskiy internationally for years. “There are some 18-year-olds that can thrive in it. But to have a 17-year-old go and be comfortable, that’s a different deal.”

Vasilevskiy’s international success helped propel him to the KHL with Salavat Ufa in 2011. Even though he spent most of his time as the team’s backup or the 1-A, he proved to be exceptionally clutch, posting a sterling 1.99 GAA in 18 playoff games with a .934 save pct.

“His last year (in the KHL) he took over the starting role,” says Brent Sopel, an NHL defenseman for 12 years who won the Stanley Cup with Chicago in 2010 and played with Vasilveskiy for Ufa in 2013-14. “He carried us. We ended up losing (in the conference finals) to Magnitogorsk, who won the Gagarin Cup. He made some unbelievable saves. The character of him, being that young age, was incredible. He had that confidence. I said [to people], ‘This guy is by far the best prospect anywhere.’”

Scouts agreed. Vasilevskiy’s size (6'3", 203 pounds), athleticism, agility and quickness earned him Central Scouting’s ranking as the No. 1 European goalie and he was invited to the 2012 NHL Draft Combine in Toronto. Three weeks later, the Lightning drafted him 19th in the first round. He was the first goalie selected. (P.K. Subban’s brother Malcolm was the second, by Boston at No. 24.)

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“There’s very few goaltenders in the history of the league that has that type of pedigree,” Frantz Jean, Vasilevskiy’s goaltending coach in Tampa Bay told SI.com during a recent phone interview. “It’s an extraordinary junior career. You can count on your fingers the amount of goalies that were able to duplicate that type of career.”

All along, Vasilevskiy has never had a problem with returning to his old backup status after a star turn. At the 2013 World Championships he was Russia’s No. 2 behind Sergei Bobrovsky of the Columbus Blue Jackets on the gold medal-winning team, going 1-0 in two games with a 0.50 GAA and .985 save pct.

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Ben Bishop felt a tweak midway through the third period in Game 2 of the Cup Final at Amalie Arena in Tampa. The score was tied 3–3 but the Lightning were trailing the Blackhawks 1-0 in the series. It was a crucial game and Bishop immediately knew that something serious was amiss.

“I made a save and I felt it,” he recently told SI.com by phone. “Kind of like ‘uh oh, what was that?’”

His plan was simple. Wait for a television timeout. Go quickly get the injury taped by the training staff. Come back in the game.

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​“They were taping it in the tunnel and then I was coming back on the ice literally as the puck was being dropped,” Bishop says. By that point, Vasilevskiy was manning the net.

There was plenty of concern for Bishop among his coaches and teammates, given how he’d carried the team to that point. He’d been sensational in the playoffs, especially while shutting out the New York Rangers at Madison Square Garden in Game 7 of the Eastern Conference Finals. Losing him now could be devastating.

“Having been a goaltender, I know those tweaks when they happen,” says Jean, who was watching from the press box. “I kind of knew it was related to a groin injury.”

With Bishop back on the bench and anxiously awaiting the next stoppage in play so he could return, a Patrick Sharp high-sticking penalty had given Tampa Bay a power play. A little over a minute-a-half-later defenseman Jason Garrison blasted a slap shot past Blackhawks goalie Corey Crawford to give the Lightning the lead. While his teammates celebrated, Bishop came back in. Vasilevskiy had not faced a shot, but his night was hardly done.

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Bishop remained in net for another 3:30, his groin barking to the point that he was concerned that he would hurt his team in a game it couldn’t afford to lose. So he skated to the bench. It was time to trust the kid.

“I knew he was a better option than me at the time,” Bishop says. “I didn’t want to not be able to make the save. I just said [to Vasilevskiy] ‘It’s just like any other game.’”

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David Alexander, the goalie coach of the Lightning’s AHL team in Syracuse where Vasilevskiy played in 2014, has a saying: For athletes to make the jump into the pro game, they need to be a pro before they get there. “And that describes Andrei the best,” he says. “He was a pro before he got to Syracuse. He was quite serious about making the NHL, was the kind of guy who put every minute he had into honing his craft.”

Each day Vasilevskiy has a routine. He stretches. He does plyometric training, a type of exercise that’s designed to build explosive muscles. He uses elastic bands to produce resistance. He rides the exercise bicycle.

“He’s like a veteran that’s been in the league a long time,” says Jean. “He doesn’t take his body for granted. He takes the time to warm up. Then he goes on the ice, he’s ready to roll. After practice, he’s got a cool down regimen that he does. It takes a lot of discipline to do that every day and do it well every day. You don’t see it much with young players. You see it with guys who have been around for awhile.”

This is not a routine that Vasilevskiy adopted upon making the NHL. It’s something he’s been doing his whole career at every level and it has driven his swift rise to the NHL.

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​“He’d stay at the rink until 3 o’clock and it’s like ‘hey, you have to go home,’” says Mike Angelidis, the captain of the Crunch. “But you don’t question his work ethic for the game.”

Vasilevskiy doesn’t simply push his muscles to exhaustion. Instead, he does smart work that’s designed to make him better in every aspect of his game.

“You find him in the gym a lot, a lot of stretching, goalie specific [drills], eye hand coordination drills, things that would make him better as a goalie,” Alexander says. “That was Andrei. That was a big part of making the jump as quick as he did.”

Vasilevskiy played only 25 games with the Crunch, going 14-6 with a 2.45 GAA and two shutouts, earning a permanent call-up to Tampa Bay in February when he supplanted veteran Evgeni Nabokov, who subsequently retired. With the Lightning during the regular season, the young Russian made 16 appearances, going 7-5-1 with a 2.36 GAA, .918 save pct. and one shutout. Teammate VladNamestnikov, a 22-year-old forward, says Vasilevskiy’s ability to make the leap to the NHL after so little time in the minors is a testament to his maturity off the ice.

“He’s already married,” Namestnikov laughs. “That says a lot.”

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With seven minutes and 41 seconds left, Vasilevskiy went back into Game 2 entrusted with a one-goal lead, the possibility of going to Chicago down 2-0 in the series still looming. There was no panic among the Lightning despite the young goaltender possessing just 45 minutes of playoff experience that included him allowing three goals in a 6–2 loss to Montreal while relieving Bishop during the second round.

“Everyone was like, ‘Vasy will do great,’” says Angelidis, who watched the game from the press box as part of the traveling “Black Aces” squad, Tampa Bay’s group of minor leaguers who were skating with the top club and trying to be ready at a moment's notice in case of injury. “We’ve seen him do it before. He’s calm.”

Vasilevskiy stopped five shots and thwarted a Blackhawks power play. He’d entered the game cold, thrust into action in the most important game of his life and he held on for the win, becoming only the fourth goaltender in 77 years to get his first career playoff victory in a Cup finals game. He was also the first since Lester Patrick of the Rangers in 1928 to get it in relief during the championship series.

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​“That’s the role of the backup,” Alexander said. “The big thing is mentally. To actually have a feel for the game can be tough. Andrei has that ability to flip the switch and focus. You’re called upon, you’re put in an uncomfortable position—that’s the true mark of an athlete.”

After the game, his teammates were incredibly excited for him. “Nervous?” Vasilevskiy replied when asked by reporters who he’d felt. “Maybe just a little bit, but after the first couple of shots I felt better. Every game I’m ready and I keep my head ready for the game and that’s it.”

“He saw it as doing his job,” says Jean. “And then he [said], ‘let’s enjoy it, but let’s get ready for the next game.’”

Bishop played in Game 3 in Chicago, making 36 saves to help Tampa Bay beat the Blackhawks 3-2 and take a 2-1 series lead. Though he was outstanding, the pain in his groin wouldn’t go away. Game 4 was now in doubt. “After the morning skate, I couldn’t even stretch,” Bishop says.

That left coach Jon Cooper with a dilemma. Go with Bishop for the chance to go up 3-1 and head back to Tampa with a chance to clinch the Cup? Or take a risk with the kid, making him the fourth-youngest goaltender in history to start a Cup Final game, and the youngest since 20-year-old Patrick Roy did it with Montreal in 1986?

“Cooper felt someway, somehow that the fact that we had three days in between Game 4 and 5 would give Ben enough time to recuperate and be ready for Game 5,” Jean says. “The decision was to take him out and let Vasy go.”

Vasilevskiy had not played all that much. He hadn’t started a game since March. Before his Game 2 stint, he’d seen only 44:59 of mop-up duty in two postseason games. But despite the pressure and the stakes, he prepared like he normally does, with his same routine and wide grin.

“I saw him the morning of Game 4,” says Sopel, who now serves as an analyst for NBC’s affiliate in Chicago as well as 120 Sports. “Not nervous at all. And that’s what makes him such a rare talent. He’s very calm, very cool and collected. The nerves never show up. Just a normal game to him.”

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It was a tightly played contest, with the Blackhawks putting only two shots on net in the first period. In the second, Chicago opened up the scoring with Jonathan Toews swatting in a bouncing puck at the 6:40 mark. After Alex Killorn tied the game five minutes later, the teams went into the third period for a tense 20 minutes that would sway the series.

At 6:22 of the third stanza, Chicago’s Brandon Saad broke the tie. Charging in from the left side, the winger came across the net and batted in a bouncing puck. The Blackhawks held on and knotted the series, but no one faulted Vasilevskiy, who’d made 17 saves and kept his team in the game the entire time.

“I was just really excited; really happy,” he said after the game. “It’s my dream to play in the Stanley Cup Final. I think I looked not bad in my first game in two months. I can play better for sure, but the first time, not bad.”

“I think he played very well,” says Al Murray, the Lightning’s director of amateur scouting who drafted Vasilevskiy. “When Saad comes across the net, Andrei actually gets a piece of the puck on a poke check and the puck bounces back to Saad. When he knocks it through Andrei’s legs, [Vasilevskiy] misses the puck by the inch. You look at the Toews goal at the other end, it was another puck that bounced up.”

“He was happy with his game, but at the same point in time, Andrei is a little bit of a perfectionist and wasn’t happy with his game because they lost,” says Alexander, who has talked with Vasilevskiy extensively during the off-season about his Game 4 performance. “The team continued to have the confidence [they have] when Ben was in net. The team kind of has a swagger when Ben is in the net. It was nice to see them continue to have that when Vasy went in under those tough circumstances.”

While the Lightning didn’t win that game or the series, McGuire believes that Vasilevskiy’s performance foreshadowed a long, stellar career.

“His work habits are impeccable, his focus is all-world, and he’s basically unflappable,” McGuire says. “That’s what we saw in the playoffs. And that’s usually the tell tale sign that a guy is going to be a superstar.”

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Bishop, who signed a two-year contract extension worth $11.9 million in August 2014 will be the Lightning’s starter next season but Vasilevskiy is clearly waiting in the wings, giving Tampa Bay the luxury of enviable depth in net.

“We’re very fortunate,” says Murray. “We have one of the top goalies (in Bishop). He’s had two incredibly strong seasons. And right behind him, we have what we feel and what a lot of people in the business feel is the best young goalkeeper in the league.”

Vasilevskiy turned 21 in July. He could very well start next season as the youngest goalie in the league. His youth and relative inexperience, though, mean the Lightning still need to develop him properly. “We just want to make sure we put him in a situation where he can continue to develop and maximize his potential,” says Jean.

It’s likely that nothing Vasilevskiy will face in his career will match the pressure, the intensity of what he went through for a few days back in June. That experience will only serve him well.

“Not many guys can say they played a Stanley Cup Final game,” Bishop says. “I don’t think he’s going to have many more tougher situations than coming into a game [like in Game 2]. Not much is going to compare to that.”

Whether it’s in another Cup Final game, an Olympics, a World Championship or just a regular game in January, one thing will remain the same. When he’s told he’ll be starting, Andrei Vasilevskiy will flash his trademark slow grin. And everyone around him will know he’s ready to go.