Now we get to find out what Bruins rookie goaltender Tuukka Rask is really made of.

His reputation as a cool customer with ice water flowing through his veins was tested down the stretch, as the Bruins played weeks worth of games at a playoff intensity just to get into the postseason. He passed the regular-season exam. Now the Finnish phenom will get his first taste of the Stanley Cup playoffs.

One thing Rask should benefit from is the familiarity he has with Boston’s first-round opponent, the Buffalo Sabres. Rask was an amazing 4-1-0 against the Sabres during the regular season, with a 1.43 goals-against average and .954 save percentage. Based on those numbers, Buffalo star netminder Ryan Miller might have to cede his probable Vezina Trophy contender status to the Bruins youngster.

Backed by Rask’s suffocating goaltending (except for the one game Tim Thomas started and blew a 2-0 lead before he was pulled), Boston won four of six from the Sabres, including one shootout and one overtime win. Zdeno Chara actually led the Bruins in scoring with 1-6-7 totals (he was also plus-9) against the Sabres. Milan Lucic scored two goals against Buffalo and Shawn Thornton seemed to be as ornery against the Sabres as he was against any team with three fights.

Miller, to his credit wasn’t too shabby, with a 1.71 GAA and .947 save percentage. Derek Roy enjoyed the most offensive success against Boston with three goals (plus one assist), while rookie defenseman Tyler Myers’ five points (two goals) led the Buffalo cause against the Bruins.

Here’s a quick look at the six regular-season match-ups between the Bruins and Sabres:

Nov. 7 Boston 4-2

Buffalo gave the Bruins a bit of a break by sitting Miller in favor or rookie Jhonas Enroth. The Bruins took the gift and ran with it, as four different players scored and Boston broke a three-game losing streak.

Nov. 20 Boston 2-1 (OT)

Making his third straight start for the first time in the NHL (Thomas was out with an undisclosed injury), Rask made 25 saves and Patrice Bergeron made sure they stand up with a tip-in of a Chara shot in the extra session. It was the second of four straight wins by the Bruins, who looked like they were about to get on a roll. Little did they know how tough their winter would be.

Jan. 29 Buffalo 2-1

Marc Savard’s return to active duty and Bergeron’s return to full-time faceoff duty weren’t enough for Boston to avoid a sixth straight loss on their way to 10 defeats in a row. The Bruins took three first-period penalties, allowed one power-play goal in that session and couldn’t climb out of the early 2-0 hole.

Feb. 9 Boston 3-2 (shootout)

Having broken their 10-game losing streak in their previous game at Montreal, the Bruins showed signs of a confidence boost. Daniel Paille burned his former team for two early goals, but the Sabres battled back and it came down to David Krejci beating Miller with a snap shot to the glove side in the fourth round of the shootout to earn Boston the extra point.

March 29 Buffalo 3-2

Head coach Claude Julien picks the wrong night to give Thomas some playing time, as the veteran netminder is victimized by some shoddy defense and some overzealous play on his own part in a one-goal defeat. The Bruins led 2-0, but Buffalo scored the next three goals and hung on to cost the Bruins greatly in the Eastern Conference race.

April 8 Boston 3-1

Booed mercilessly in Boston’s previous home game and throughout the night (including after his turnover leads to an early Buffalo goal), Dennis Wideman recaptured the home crowd’s hearts with the game-winning goal. For the second time this season, the Bruins get the advantage of facing Buffalo’s back-up netminder, this time Patrick Lalime, but the win counts just as much in the standings and the Bruins moved within two points of a playoff berth.

It’s hard to believe that during a mediocre season as a whole, the Bruins played their best hockey against the team that won the Northeast Division. They owe a lot of their success to the netminder that stifled the league’s eighth-best offense, so there’s little doubt the biggest spotlight in this series for the Bruins will be securely focused on the crease and 23-year-old Tuukka Rask.