He has learned to control his emotions both on and off the ice, which is a big reason he's been so successful this season. When the Bruins begin their first-round playoff series against the Buffalo Sabres on Thursday night at HSBC Arena, Rask will be in net. The 23-year-old Finland native earned the right to start because if it weren't for him, the Bruins wouldn't still be playing.
With Rask getting the nod from coach Claude Julien, Tim Thomas, the reigning Vezina Trophy winner as the NHL's top goaltender, will serve as the backup. It's been a natural progression at the position for the Bruins this season, but even with Rask comfortable in his surroundings, he really doesn't know what to expect in terms of intensity and emotion in the Stanley Cup playoffs.
He'll say all the right things and do all the right things. But the fact of the matter is that he has never experienced the kind of hockey he's about to.
So it wasn't surprising to see Thomas talking to Rask after a recent practice about what to expect. It was a sincere discussion off in the corner of the locker room at Ristuccia Arena, and Rask will take from it what he can. On the other hand, maybe ignorance will be bliss for Rask once the puck drops.
"It's the best time of a player's season -- the playoffs," Rask said. "I'm really excited. It's the same game, just a different atmosphere out there, and you just try to play the same way you have throughout the year."
Not that it's truly comparable to the NHL, but Rask has played at a highly competitive level in two postseason runs with Boston's AHL affiliate, the Providence Bruins. Last season, he led the P-Bruins to the Eastern Conference finals of the Calder Cup playoffs, compiling a 9-6 record with a 2.21 goals-against average and a .903 save percentage.
Rask struggled in his first postseason run with the P-Bruins in 2008, posting a 6-4 record in 10 playoff games with a 2.18 GAA. He allowed too many easy goals and couldn't make the critical saves when needed, forcing some in the organization to doubt his ability.
"Maybe my first year I was a little too excited," Rask said. "I knew we had a great team and I think I got carried away there. Last year, I played the same way I did during the year and I didn't change a thing. That was the biggest difference in those two years. I learned to keep myself calm."
That experience and learning curve translated into success in his first full season with the Bruins.
It didn't take long for Bruins forward David Krejci to realize how good Rask was when the two played together in Providence in the 2007-08 season. But Krejci did wonder whether Rask could be successful at the NHL level.
"He's made a huge step," Krejci said. "When I played with him in Providence, I knew he was a great goalie. He's someone special, but we didn't know how good he would be once he got to the NHL. He's proved it, and he's one of the top goaltenders in the league.
"Now that we're in the playoffs, he'll show the numbers he had during the regular season don't lie. We count on him big time because we've had some trouble scoring goals. Hopefully if we get a couple of goals, he can stop all the shots and hopefully we'll win games by the score of 2-0 or 2-1."
When the Bruins acquired Rask from the Toronto Maple Leafs for goalie Andrew Raycroft on June 24, 2006, Leafs fans weren't happy the organization had surrendered its top pick (21st overall) in the 2005 NHL draft. The Bruins, however, were thrilled with Rask's potential, and they handled his development perfectly.
"We felt when we made that decision to have him here this year that he was ready," Julien said. "The one thing we talked about is how are we going to bring him in. We certainly didn't want to throw him to the wolves. We wanted to give him an opportunity to slowly work his way in. The more confidence he got, the more he got to play."
Julien also credits Thomas with helping Rask's development this season because the Bruins had the luxury of having two quality goaltenders and didn't have to rush Rask into action.
"He just got better and better and got to the point where he was so good, you couldn't do otherwise but keep putting him in," said Julien. "It's as simple as that. A lot has been said about Timmy, but it's not about Timmy, it's about what Tuukka has done."
Rask posted a 22-12-5 record in 45 games with league-leading tallies of a 1.97 GAA and a .931 save percentage.
When it was time to ride one goalie down the stretch and into the playoffs, Julien decided to stick with Rask.
"Logic took over," Julien said. "It's as simple as that."
The coach has made his decision, and he's standing behind it.
"I don't think we're going in there with doubts. You don't think that way," Julien said. "You go in there with your team and you're ready to go to battle. I'm not going into the playoffs with question marks in my mind. I'm going into the playoffs with certainty that our guys are ready to go."
It's clear Rask is ready to go and doesn't seem concerned about the pressure of the playoffs. If he can focus on the task at hand, it's very possible he could play well enough to keep the Sabres at bay and help the Bruins advance past the first round.
"If you think about it too much, it takes you off your game a little," Rask said. "But if you stay calm and stay focused, it'll be good."
Although this will be Rask's first rodeo at this level, the masked man at the other end of the ice is a proven world-class netminder.
Buffalo's Ryan Miller played more games (69) and finished a close second behind Rask with a 2.22 GAA and a .929 save percentage. Because both goaltenders are solid, this series could be a low-scoring affair with the better goalie leading his team to victory.
There are obvious differences between the two, and if there's anyone with a sound understanding of both of them, it's Thomas. He has had an inside look as Rask's teammate with the Bruins and as Miller's backup for Team USA at the Winter Olympics in Vancouver, British Columbia.
"I don't know if it was just because of the Olympics, but he prepared the same way for every game there," Thomas said. "He's one of those guys who is intense and gets in net and really mentally prepares himself for a game. Some guys don't do that as much. Marty Brodeur is better off not really even preparing, just going out and playing because he's played so much and for so long. Ryan Miller really thinks each game over and mentally prepares. You can see it in his intensity and in his face. He is the same way for every game."
"Tuukka is more like I am, or somewhere in the middle," Thomas said. "He's not like Marty Brodeur, who is really relaxed. Tuukka's relaxed, but he's getting ready at the same time. He's kind of the middle ground."
Bruins vice president and Hall of Famer Cam Neely recently referred to Rask as "cool as a cucumber" and said he has faith in the rookie in the upcoming playoffs. Rask has an opportunity to cement himself as the cornerstone of this organization -- win or lose.
He's been given the opportunity, and he's ready for the challenge.
"Of course every player will be remembered for the postseason," Rask said. "It doesn't matter if you play good in the regular season if you suck in the playoffs. You try to be as good as you can and make a great run."
Rask's run is only beginning.
Joe McDonald covers the Bruins and Red Sox for ESPNBoston.com.