Thomas stopped 16-of-17 Montreal attempts during the third period and improved to 16-5-0 this season, as the Bruins won their sixth straight and 10th in 12 home games.
Montreal lost for the ninth time in 12 games -- and dropped its second straight game under interim head Coach Randy Cunneyworth, who replaced the fired Jacques Martin Saturday.
Carey Price made 28 saves for the Canadiens.
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