Netminder Carey Price was credited with 26 saves on 28 shots for the Canadiens, who started a seven-game homestand with a victory after losing three of four.
Buffalo's Thomas Vanek scored twice, once on the power play in the first period and once in the second.
Goaltender Patrick Lalime was beaten three times on 34 shots for the Sabres, who had won two in a row.
On the power play, Montreal was 0-for-5, while the Sabres went 1-for-5.
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