The Stanley Cup is up for grabs, and this year's playoffs are shaping up to be wacky.

The Calgary Flames were eliminated by the Colorado Avalanche after losing 5-1 in Game 5 on Friday night, meaning the top seeds in both conferences have been ousted in the first round. The Tampa Bay Lightning, the No. 1 seed in the Eastern Conference, were swept by the Columbus Blue Jackets earlier in the week.

It's the first time in NHL history that both conference top seeds were eliminated in the opening round of the Stanley Cup playoffs. The Lightning, who matched an NHL record with 62 regular-season wins, and the Flames combined for only one win in their first-round exits.

"Obviously we had high expectations for ourselves. Had a great regular season, kind of played a little flat-footed there in a couple of games. And now the season's over," said Johnny Gaudreau, Calgary's top goal scorer who was limited to one assist in the series. "It sits with you for a while, probably until the end of the playoffs. It's going to be a long couple of months. Hopefully it sits well with us, we learn from this, and come back next year and learn from this."

In the NBA, the teams with the best record in each conference have never both been eliminated in the opening round; however, it has happened five times in MLB during the wild-card era (2000, 2002, 2008, 2011, 2014), according to the Elias Sports Bureau.

The Avalanche won four straight games to complete a 4-1 series win over the Flames, marking Colorado's first playoff series win since 2008. The Avalanche, who had the NHL's 17th-best record during the regular season, will face the winner of the Vegas-San Jose series, which the Golden Knights lead 3-2.

"It's awesome to win a round,'' said Avs center Nathan MacKinnon, who had three goals and five assists in the series. "It's been a while for this organization, and I, personally, have never won a round, so I'm really excited about it.

"Obviously we were the big underdogs, and no one picked us to win. I didn't expect to win it in five, but we believed in this group."

The Flames had the NHL's second-best offense, averaging 3.52 goals per game. Yet after defeating the Avalanche 4-0 in Game 1, Calgary managed only seven goals over the next four losses.

Flames goaltender Mike Smith, making his first postseason appearance in seven years, had a rough time in the series, especially when his team left him to dry by allowing 56 shots in Game 3, a 6-2 Colorado win.

"I don't think we played our best consistently through this series, and you have to be your best if you want to move on," Smith said. "You can't move on just being average, and they were the better team. They deserve some credit. They snuffed us out offensively and did a good job to shut down our top guys. You always got to remember that there's two teams on the ice, so you have to give a lot of credit to the way that they contained us."

Calgary coach Bill Peters decided to make veteran winger James Neal a healthy scratch in the do-or-die Game 5. Neal, 31, signed a five-year, $28.75 million deal in free agency after a long playoff run with the Vegas Golden Knights last spring. Neal underperformed this season, scoring a career-low seven goals.

The Avalanche won Game 2 in overtime, thanks to a goal by MacKinnon. Colorado got a boost in Game 3 with the arrival of recently signed college player Cale Makar, the 2019 Hobey Baker Award winner. Makar's University of Massachusetts team lost in the NCAA title game last Saturday night. By Sunday, he signed his NHL contract, and on Monday, he made his NHL debut and scored a goal, to boot. Makar is a Calgary native and his parents happen to be Flames season-ticket holders.

Information from The Associated Press was used in this report.