ST. LOUIS -- With the Boston Bruins facing elimination Sunday, Tuukka Rask came up big.

Perhaps you've heard this story before.

Rask was once again exceptional for Boston, making 28 saves -- including one that rolled off his back -- as the Bruins defeated the St. Louis Blues 5-1 to force a Game 7 on Wednesday.

It has been a familiar trend for Boston this postseason: Rely on the 32-year-old Finn when it matters most. In three games in which the Bruins faced elimination this postseason -- Sunday's Game 6, along with Games 6 and 7 of their first-round series against Toronto -- Rask is 3-0 with a 1.33 goals-against average and .953 save percentage, allowing only four goals.

"He's been a big reason why we're in this position," teammate Patrice Bergeron said. "He was definitely in the zone."

Added defenseman Charlie McAvoy: "He just steps up when it matters, and we have all the faith in the world in him, and to see him play the way that he did, it's really not a surprise to us. We just believe in him so much, and we know the kind of person and player he is. He's our rock."

It was all the more impressive considering the atmosphere in St. Louis. Before puck drop, nearly 30,000 fans poured into a downtown square surrounding the arena, and the crowd buzzed as the Blues looked to clinch their first Stanley Cup in franchise history. St. Louis came out aggressively on the forecheck, maintained possession and had the first power play as it began the game with a 5-1 lead in shots. Rask took it from there.

St. Louis finished 0-for-4 on the power play. Many Bruins players called Rask their best penalty killer.

"We killed that penalty in the first period. That's huge," Rask said. "Last time we were here, they scored 30 seconds in. Obviously you don't want that to happen again. We weathered the storm pretty good and then got the lead. It was a great start."

Rask's unflappability has been apparent in these playoffs. In interviews throughout the postseason, he has never wavered in tone. He has exuded confidence and calmness.

With another standout performance Sunday, Rask catapulted to the favorite for the Conn Smythe Trophy as playoff MVP. After all, no goalie has played as many games in a playoff year as Rask's 23 while posting a better save percentage than his current mark of .938 besides Tim Thomas, who led Boston to its most recent Stanley Cup in 2011 with a .940 save percentage in 25 games. Rask was the backup on that team.

Rask pitched a shutout through two and a half periods and was close to becoming just the fourth goalie in the past 60 years to record a shutout on the road while facing elimination in a Stanley Cup Final. The others in that elusive group: Thomas, Ed Belfour and Patrick Roy.

Perhaps Rask's most ridiculous save came in the second period, when a puck bounced off the post and deflected off Rask's back before McAvoy batted it away.

Rask had already seen a replay by the time he met with reporters.

"I didn't know where it was, and I figured it might be somewhere behind me, so I just tried to corral it with my hand behind my back -- and then it stuck in my pants, and then it fell somewhere," Rask said. "I think Chucky made a great play to keep it out of the net originally, and it's never a good thing for a goalie to kinda be facing the play with your back, but luckily it stayed out."