The Bruins improved to 14-0-1 in their last 15 games, their longest point streak since the club went 17 games without a loss in 1983. The defending Stanley Cup champions clamped down on the Eastern Conference-leading Penguins, holding star Sidney Crosby scoreless and dominating the game for long stretches.
Matt Cooke scored his sixth goal of the season for Pittsburgh, but the Penguins went 0-for-4 on the power play and squandered a pair of 5-on-3 opportunities.
Boston had no such issues. Seguin's power-play goal early in the third period gave the Bruins a 3-0 lead, and Thomas had little trouble making it hold up while winning his 10th straight game.
The Bruins hardly looked like the team that slumped out of the gate in October. They've righted themselves over the last month, roaring to the top of the Northeast Division lead with a nearly flawless November, winning 12 of 13 games and grabbing a point in a shootout loss to Boston. They haven't lost in regulation since dropping a 4-2 decision in Montreal on Oct. 29, the longest streak of earning at least one point in a game since 1983.
While praising his team's resilience, Boston coach Claude Julien pointed to this week's three-game in four-day stretch as a better litmus test for how far the Bruins have come. Boston travels to Winnipeg on Tuesday before hosting Southeast Division-leading Florida on Thursday.
Judging by the way they pushed the Penguins around, the Bruins are more than up to the task.
The Penguins came in 5-1-1 since Crosby returned from concussion-like symptoms two weeks ago, yet they found little room to maneuver in a game more suited to April than December.
Boston kept the former MVP in check — he finished with five shots in just over 21 minutes of ice time — and never let Pittsburgh's high-powered attack get in gear, even on the power play.
The Penguins looked disorganized at times and dead in the water on others with the man advantage. They failed to score on a pair of 5-on-3s, including a listless full 2 minutes two-men up in the second period that produced only one quality scoring chance that Thomas easily turned away.
The Bruins controlled a tight first period, and Campbell gave them the lead 2:57 into the second, taking a feed from Daniel Paille and then chopping it past Pittsburgh's Marc-Andre Fleury while getting whacked to the ice by Craig Adams.
Pouliot pushed the lead to 2-0 less than five minutes later, sizzling a wrist shot over Fleury's glove. The Bruins kept pressing, with Seguin scoring his 13th of the season off a brilliant feed from Patrice Bergeron, the first power-play goal allowed by the Penguins in their last 10 games at Consol Energy Center.
Cooke briefly gave the Penguins life when he tapped in a pass from Joe Vitale to get Pittsburgh on the board with 9:04 remaining. Vitale backed up his assist by taking down Campbell in a spirited brawl shortly after the ensuing faceoff.
The Penguins started peppering Thomas, but the reigning Vezina Trophy winner had little trouble keeping the Bruins nearly perfect since Halloween as Pittsburgh struggled at times to get out of its own way. Crosby and linemate Chris Kunitz collided near center ice in the third period, with both players laying on the ice for several seconds before slowly making their way to the bench. Crosby's head came nowhere near Kunitz or the ice on the play and he returned to action a couple of minutes later.
His presence, however, could do little to slow down the streaking Bruins, who pulled within one point of Pittsburgh in the conference standings.
NOTES: Jordan Caron and Steven Kampfer were scratched for the Bruins while Zbynek Michalek, Deryk Engelland and Richard Park were scratched by the Penguins. ... Pittsburgh's 23 shots in the third period were a season high. ... The Penguins also played without D Kris Letang, who missed the game with a broken nose.