Matt Frattin and Phil Kessel also scored for the Leafs, who won for the first time in four games and dealt the playoff-hopeful Sabres a stinging setback.
Ben Scrivens nailed down the win with 29 saves.
Buffalo, meanwhile, lost a second straight and fell two points behind Washington in the race for the eighth and final playoff spot in the Eastern Conference with three games remaining.
The Capitals bested Montreal 3-2 in a shootout Saturday.
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