The Bruins' penalty-killing unit was going to have to come up big if Boston was to pull out two points against a dangerous Tampa Bay hockey club Thursday night. So it’s no surprise the B's emerged with a 4-2 victory since their penalty killers went a perfect three-for-three against the high-powered Lightning. The Bruins lead the NHL in killing off 94.4 percent of the power plays they face, and have allowed a grand total of three PP goals in 54 chances this season. Tampa Bay came into the game scoring on 25 percent of its PP chances, but the Bruins silenced that part of the Bolts' game. High effort PK work from Patrice Bergeron, Brad Marchand, Gregory Campbell, Daniel Paille and Rich Peverley helped, and Johnny Boychuk and Dennis Seidenberg did yeoman’s work with over three minutes of ice time logged on the penalty kill on a hot, humid night in Tampa. Tuukka Rask is also obviously a key part of the penalty-killing efforts, and he says it takes certain qualities to keep natural PP weapons like Steve Stamkos and Marty St. Louis off the board. “You know what? It’s been building over the years,” said Rask. “[Former assistant coach Craig Ramsay] was a PK guru for us when he was here and [current assistant Doug Houda] has come along in his footsteps the last few years. We just battle really hard and we knew what we’re supposed to do. It’s just going out there and executing 110 percent, and the [penalty kill] has been our bread and butter.” The turning point in the game arrived when the Bruins, clinging to a one-goal lead, killed off a power play to start the third period with their best penalty killer, Zdeno Chara, in the box for a (bogus) roughing call. “What we talked about coming into the third [period] was that we needed a big kill . . . " said coach Claude Julien. "Our guys responded well."