By Matt Kalman, CBS Boston

BOSTON (CBS) — After making 11 saves on 12 shots in the first period Thursday, Bruins goaltender Tuukka Rask screwed up.

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Not long after the second period started, Rask misplayed a puck onto the stick of Toronto’s 508-goal scorer Patrick Marleau. Rask got back to in position to make a save and keep the score tied, and all the miscue did was pad Rask’s save percentage.

As it turned out, Rask didn’t need any gimmicks to boost his stats because he was forced into the rare position of having to carry the Bruins over the course of Game 4 of the Eastern Conference first round against the Maple Leafs.

Rask responded with 31 saves on 32 shots in a 3-1 win. The Bruins lead the best-of-7 series 3-1 heading into Game 5 in Boston on Saturday.

The night started out with a shock to the system when it was revealed center Patrice Bergeron was out with an upper-body injury. The Maple Leafs nearly made matters worse for the Bruins 5:30 into the game, when Mitch Marner stole a David Krejci back pass and took off on a 2-on-1 with Marleau.

Marner’s pass to the front was perfect, but so was Rask’s positioning and he made the save to keep the score 1-0 Boston. That was an early sign that Rask was determined to make sure he filled the void left by the absence of the Bruins’ most valuable player, and if the Bruins needed him to be Superman he was ready to soar. Little did he know how much the Bruins were going to rely on their goaltender to keep the game tight while they tried to grind out a victory without Bergeron.

Instead of sustaining much time in the attacking zone, the Bruins found their offense in spurts. They took a 1-0 lead before anyone on either team broke a sweat when a seeing-eye shot by Torey Krug entered the net 28 seconds into the game. They grabbed a 2-1 lead when Brad Marchand cashed in on David Pastrnak’s end-to-end rush. And then they extended their lead when Jake DeBrusk did the same for on an end-to-end rush by David Krejci.

Other than those three possessions, it was mostly a night for the Maple Leafs to take aim at Rask and for him to do something the Bruins ask him to do occasionally: Save their rear ends.

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The Maple Leafs won the shot-attempt battle 77-40. Rask got some help from 27 blocked shots, but that number was more indicative of how little the Bruins had the puck than any strategy to stop the Maple Leafs.

When the puck got through the layers of defenders, Rask was sharp. He gave up the one Maple Leafs goal on a one-timer from the high slot by Tomas Plekanec after a pass by Marner from his knees.

Shortly after, Rask had an amazing sequence where he used his right shoulder to stop Jake Gardiner’s shot through traffic and then denied Zach Hyman on the rebound with the left pad. Boston’s often-disrespected goaltender stopped a Marner breakaway in the second. And as the cherry on top of the sundae, he adjusted his positioning just right to deny Connor Brown’s tip in the third period.

The Bruins continued to struggle with their puck management and didn’t play below the dots in the Toronto zone enough. They spent too much time in their own end and had a few shifts, especially in the second period, when their defense pairs got mixed up and the result was sloppy play.

But Rask, who had a .911 save percentage through three games of this series, was the difference maker. It was a rare virtuoso performance, not because of Rask’s abilities, but because of the way the Bruins play in front of him. The notion that he doesn’t steal the Bruins games is contradicted by the Bruins surrendering the second-fewest shots in the NHL in the regular season. He doesn’t have to “steal a game.” The idea that he doesn’t make the difficult saves, or the ones that he’s not supposed to make, is cancelled out by every goaltending expert’s observation that Rask is proficient at anticipating the shots and being in the right position so he doesn’t have to bust his groin to keep the puck out of the net.

No one would’ve had the right to blame Rask if Marleau’s first-period redirection lit the lamp. Rask would’ve been forgiven had Marner beat him on that breakaway.

Even Rask’s own gaffe in the second period didn’t do in the Bruins, and he was able to carry them to victory without them playing anything close to their best. A game that could’ve been a disaster, and possibly the start of a catastrophic conclusion to this series (especially if Bergeron doesn’t return soon), turned into the type of signature moment Rask rarely has the chance to create and a triumph that has the Bruins one win from the second round.

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Matt Kalman covers the Bruins for and also contributes to and several other media outlets. Follow him on Twitter @MattKalman.