Glen Murray, Mark Mowers, Milan Jurcina, Patrice Bergeron and Marc Savard had the goals as Boston held on for a 5-3 victory over the Chicago Blackhawks on Friday night.
The Bruins, who led 4-0 after two periods, improved to 4-0-1 in their last five games and 5-1-1 in their last seven. But Chicago rallied on goals by Jim Wisniewski, Bryan Smolinski and Denis Arkhipov in a 4:19 span early in the third to cut it to 4-3.
Thomas, who stopped 37 shots, made his most spectacular save with 1:44 left in the third. With the score still 4-3, he sprawled across the crease to catch Jeff Hamilton's point-blank attempt.
"It was actually an, 'Oh, no!' moment, as in, 'Oh, no! He's got a wide-open net,' " Thomas said. "I was just trying to stay with him. It felt great to make that save.
"But it was 4-0 going into the third period. I had no idea a save at the end of the third period was going to be a big save."
Savard's empty-net, power-play goal with 11 seconds left sealed Boston's victory.
Boston coach Dave Lewis was satisfied with the win, but more impressed by Thomas' focus.
"That was a good one (save)," Lewis said. "He never quits on a puck.
"That's what goalies are supposed to do. Winning a game is never a bad thing. You try to draw from your experiences. Our guys found a way to win. Maybe two or three months ago, we'd have lost this game."
Bergeron extended his point streak to 10 games. He has six goals and 11 assists during the span.
Thomas lost a bid for his second shutout this season - and second in four games - when Wisniewski scored 1:35 into the third to launch Chicago's comeback attempt. The Blackhawks are 9-4-3 since Denis Savard took over as coach on Nov. 27.
Chicago's Nikolai Khabibulin made his 10th straight start but was pulled for the first time this season after allowing three goals on seven shots in the first period.
Brian Boucher replaced him to start the second, and permitted one goal on 13 shots.
"The focus didn't seem to be there early," Denis Savard said. "We were undisciplined and soft on the puck.
"We had a couple of possessions where we just gave it up. We left Habby (Khabibulin) by himself after guys gave the puck away for no reason."
Boston jumped out to a 3-0 lead in the first on goals by Murray, Mowers and Jurcina.
Murray opened the scoring 5:51 in, tipping in P.J. Axelsson's shot at the edge of the crease
Mowers' short-handed goal with 3:42 left in the first made it 2-0. From the low edge of the right circle, Mowers spun and surprised Khabibulin with a low shot.
Just over a minute later, Jurcina extended Boston's lead to 3-0, scoring on screened shot from the top of the right circle.
Bergeron's power-play goal with 4:53 left in the second made it 4-0. He knocked the puck in from the edge of the crease following a turnover by Jassen Cullimore.
The Blackhawks scored three times early in the third to cut it to 4-3. Wisniewski connected on a screened shot from the top of the right circle at 1:35 while the teams were skating 4-on-4 to make it 4-1.
Smolinksi was credited with cutting it to 4-2 45 seconds later when Lasse Kukkonen's shot struck him in the back, popped into the air and landed in the net.
Arkhipov made it 4-3 at 5:54 when he rammed in a rebound of Radim Vrbata's shot.
The Blackhawks had several good chances later in the third, but missed the net or were stopped by Thomas.
"We took it to them in the third period and I think that's the approach we want to take," Boucher said. 'We had a great chance to tie it and Thomas made a key save.
"But nevertheless you can't wait until the third to get it going."
Notes: The Bruins and Blackhawks faced each other for the first time since Feb. 14, 2004 . . . The crowd of 19,315 was Chicago's largest this season . . . Hamilton returned to the lineup after missing three games with the flu and a hip flexor injury . . . Blackhawks D Jim Vandermeer was a healthy scratch for the third straight game . . . Boston C Yan Stastny was a healthy scratch . . . Chicago F Peter Bondra, who scored his 500th NHL goal last week, took a hard hit to the upper body from Bruins D Brad Stuart just 27 seconds into the game. Bondra returned at the start of the second period. After the game, Savard said Bondra had suffered a shoulder injury and would be examined Saturday . . . Boston F Jeff Hoggan left after the first period with an upper body injury.