Glen Murray supplied a tie-breaking goal at 5:35 of the third period, but it was the play of Thomas that was the difference in a 4-1 Boston victory. Toronto outshot Boston 46-24. Marco Sturm and Brad Boyes added late-game insurance for the Bruins. It was the seventh win for the Bruins in their last nine games, and three of the wins have been over the Leafs.
Goals by Shean Donovan and Nik Antropov in the second period had sent the teams into the third tied 1-1.
Toronto defenceman Bryan McCabe left in the dying minutes with an injury to his left knee.
It was the fourth time in nine games that Boston was Toronto's opponent. The Leafs won 6-4 (Nov. 9) and Boston won 2-1 (Nov. 16) and 3-1 (Nov. 25) before the Northeast Division rivalry was renewed in front of a capacity Air Canada Centre crowd of 19,469.
Donovan opened the scoring at 5:59 of the second period when he took a wrist shot from the circle to the right of goaltender Andrew Raycroft that deposited the puck in the far top corner of the net. It was the first goal of the season for the former Calgary Flames forward.
It was 1-1 when Antropov got credit for a goal after a video review overturned referee Kevin Pollock's initial ruling. Mike Peca took a shot, Antropov braked as he skated into the crease, and the puck struck his skate blade and ricocheted into the net at 15:39. Pollock waved it off, and the video goal judges studied it long and hard before awarding Antropov his fifth goal of the season.
Toronto got a golden opportunity to grab the lead early in the third period when Wayne Primeau was sent off for hooking at 2:07 and Andrew Alberts for high-sticking Matt Stajan at 2:26, but Thomas easily stopped the two long shots the Leafs managed during the two-man advantage that lasted 1:41.
Boston regained the lead at 5:35 when Petr Tenkrat set Murray up in the circle to the left of Raycroft. Murray's slap shot sent the puck into the top corner on the short side of the net - Raycroft's glove side again. It was Murray's team-leading 12th goal of the season.
Sturm broke free for a clear shot at Raycroft and slid a shot between the goalie's legs for his fourth goal of the season at 17:07, and Boyes added an empty-netter with 23.4 seconds remaining.
Notes: On power plays, Toronto was 0-for-6 and Boston was 0-for-3. . . . Earlier Tuesday, the Leafs traded third-string goaltender Mikael Tellqvist to the Phoenix Coyotes for right-winger Tyson Nash, a former NHL agitator who has been playing for the AHL team in San Antonio, Texas, and a fourth-round 2007 draft pick. Nash will report to the Toronto Marlies. . . . D Jay Harrison cleared waivers and was assigned to the Marlies. . . . D Pavel Kubina wore No. 31 instead of his usual 73. . . . Free-agent pitcher Gil Meche was the guest of Blue Jays GM J.P. Ricciardi at the game. . . . Toronto is at Atlanta on Thursday and at Montreal on Saturday. . . . The Leafs and the Bruins meet a fifth time next Thursday in Boston.