Reilly Smith's short backhander with 58.7 seconds remaining in regulation slipped through Thomas' pads for the game-winner to lead the Boston Bruins to a 3-2 win against the Florida Panthers at BB&T Center.
Thomas, who won the Vezina Trophy and Conn Smythe Trophy in 2011 after leading Boston to the Stanley Cup title, ended up stopping 37 shots in his return to action. He had missed Florida's previous four games because of a groin injury sustained Oct. 8 during a 2-1 loss against the Philadelphia Flyers.
"I, of course, tried to approach it just like any other game," Thomas said. "Having said that, it was a big game for me coming back after a while and then obviously facing your former team and a lot to-do around it. I was a little bit nervous today, but not too bad. I just tried to approach like any other game.
"You know what, I probably should have wanted to win worse because I didn't go into it with that kind of vengeful attitude: 'Oh, I want to beat my old team.' I went into it approaching it like any other game. There wasn't that factor."
With the amount of attention given to the Thomas-Bruins matchup, from the large contingent surrounding the goalie's locker to the splash page on the Panthers' website trumpeting his return and his battle against his former backup, Tuukka Rask, it clearly wasn't any other game.
"It was different, especially when you play with a guy for so many years, a part of the big group here," said Bruins forward Daniel Paille, who scored the first goal of the game at 3:45 of the first period. "So it's definitely different when you play someone on the other side, but we've all moved on and realized we had to play this game."
The game appeared headed to overtime before Smith, who was acquired in the offseason trade that sent Tyler Seguin to the Dallas Stars, scored his first goal in a Boston uniform on a seemingly harmless backhander from the left circle.
Thomas said he was fooled by a changeup.
"Yeah, changeup," Thomas said. "The way his stick was angled and the puck, it wasn't laying exactly flat. I thought he was going high blocker with it, and it was just enough to get me to move my stick out of the way and to open up to start taking away that upper blocker. That was a tough one."
Dougie Hamilton also had a first-period goal to stake Boston to a 2-0 lead, and Rask finished with 27 saves.
Rask described the experience of playing against Thomas as "fun."
"A little weird at the start to see him over there, but it's tough to see what the other guy does and just focus on saving that puck," Rask said. "It was definitely an experience."
The game was the first of five meetings between these new Atlantic Division rivals. The Bruins have now won the last four meetings after sweeping three games last season and outscoring the Panthers 11-2 in the process.
"I can't say we're pleased with our game tonight," Bruins coach Claude Julien said. "We had a 2-0 lead and we started letting up a little bit, got away from our game and started getting cute, and gave them an opportunity to get back in the game. We've won some games in this building, but I don't recall us playing really well here."
The Bruins (4-2-0) improved to 2-0 away from Boston in the first game of a three-game road trip that continues Saturday against the Tampa Bay Lightning.
Thomas, who won 196 games and the Vezina Trophy twice during eight seasons with the Bruins before sitting out last year, was beaten on Boston's third shot.
Paille was streaking down the left side when he took a pass from Dennis Seidenberg. Paille got past defenseman Erik Gudbranson and fired a shot high on the short side to beat Thomas, who had begun to go down.
Hamilton increased the lead to 2-0 at 12:47 with a power-play goal that snapped the Bruins' 0-for-12 drought with the man advantage.
With Zdeno Chara screening Thomas in front of the net, Hamilton scored with a slap shot to the glove side. Hamilton had been a healthy scratch in Boston's previous two games.
"I don't think that goal goes in if [Chara is] not there," Hamilton said. "It would have been right in the glove. When you know he's there, you take any shot you can get. We've been talking to try to get it up and make them save it with their hands and if they can't see it, that's pretty tough. Z creates that goal."
The Panthers broke through at 7:28 of the second period thanks to two nice passes by Jonathan Huberdeau.
Huberdeau skated the puck up ice on a delayed penalty before dropping it to Tom Gilbert at the blue line. After Gilbert got the puck back to Huberdeau in the corner, he slid a quick pass to Versteeg, who skated in and beat Rask with a high wrist shot from the bottom of the right circle.
Boston couldn't cash in on a four-minute power play in the third period. The best chance during that man advantage came when Jarome Iginla stickhandled past two Panthers players and came in alone on Thomas, only to be stoned by a pad save.
Thomas also stopped a 2-on-1 in the first period with a blocker save on a wrist shot by David Krejci.
Early in the second period, Thomas stopped another 2-on-1 when he quickly moved over to get his leg on a redirection by Iginla off a pass from Milan Lucic.
Early in the third period, Rask stopped defenseman Matt Gilroy from the front of the net to preserve Boston's 2-1 lead.
Florida tied the score with exactly six minutes left in the third period off a faceoff when Rask couldn't handle a puck that slid to him. After the puck became loose in front of Rask, Winchester scored on his second whack at it.
"I didn't want to cost us the game," Rask said. "I made a mistake there and they tied it up. You just want to get the win. We had an opportunity to close it out before that and we gave them a chance to tie it up. The guys came up big after that."
After Florida tied the game, Boston had seven of the next nine shots on goal. Thomas steered them all away until Smith's backhander put a damper on his night.
"He's a tremendous goalie," Paille said. "We had 40 shots and it still took us until that last minute. It was nice to get a couple early on him and have that lead, but he bounced back and made it that much harder to get that third one."