The Eastern Conference lead will be on the line Sunday in another black and gold battle in Pittsburgh, where the hometown team will be trying for a ninth consecutive victory.
The Bruins led 2-0 with seven minutes to play Tuesday at Consol Energy Center, but a goal by Chris Kunitz and two from Brandon Sutter suddenly swung the game in the Penguins' favor before the end of regulation.
"They were true to form," Pittsburgh coach Dan Bylsma said of the Bruins. "They're a tough team to play against and they play well defensively. Their penalty kill was good against our power play. But I like the fact that our team kept playing and kept playing."
This matchup between East heavyweights features Pittsburgh's prolific offense - averaging 3.7 goals to lead the league - against Boston's stingy system, which is yielding 2.1 goals per game to rank among the NHL's best.
Lately, the Penguins (21-8-0) have found enough goals in the series. They've tallied 15 while winning four in a row against the Bruins, even with Sidney Crosby missing two of those games and going without a point Tuesday.
Crosby was also held off the scoresheet Saturday, but it didn't matter as Pittsburgh beat the New York Rangers 3-0. Tyler Kennedy had a goal and an assist and Marc-Andre Fleury turned aside 23 shots for his franchise-record 23rd career shutout and first this season.
The Penguins have totaled 36 goals while going 8-0-0 in March, even with reigning league MVP Evgeni Malkin - still out indefinitely - missing five of those games with injuries. They've been especially good late in games, outscoring their last four opponents 9-0 in the third period.
"We want to play a full 60 minutes," forward Pascal Dupuis said. "We invest early in games by putting pucks behind their defensemen, by hitting their defensemen, by playing in the offensive zone. It looks like lately it's tiring teams down."
The Bruins (19-4-3) played a complete game Saturday, avenging another recent meltdown with a 4-1 win over Washington. The Capitals had erased a three-goal deficit to beat Boston 4-3 in overtime March 5.
Boston never looked back Saturday after Nathan Horton and David Krejci scored in the first period, both off passes from Milan Lucic.
"They showed exactly what we need to see from them on a more consistent basis," coach Claude Julien told the Bruins' official website about the Horton-Krejci-Lucic line. "They were skating the north-south type game, they were forechecking, being physical.
"You want to keep that line going the way they have been tonight because they're a big asset to our hockey club."
Matinee games were a liability for the Bruins last season, when they went 6-7-2 in the afternoon, but they're 5-0-0 in such games in 2013.
Their loss in Pittsburgh was only their second in regulation on the road this season. Boston's league-best penalty kill has gone 46 for 47 away from home, including 4 for 4 against the Penguins.
Fleury may get his second start in 24 hours, especially considering he's 7-2-0 with a 1.78 goals-against average in his last nine versus Boston.