Alex Steen had a goal and assist, and Pavel Kubina also scored in a game the Maple Leafs never trailed. Sundin's two assists gave him 495 with Toronto, moving him into third on the team's career list, two ahead of former captain Dave Keon.
Toronto snapped a two-game losing skid and won on the road for only the third time in nine games (3-5-1). The Leafs (20-19-6) won despite missing six regulars due to injury - including forwards Michael Peca and Darcy Tucker - after defenceman Ian White hurt his shoulder in a 4-1 loss to Carolina on Tuesday.
Chris Drury and Thomas Vanek scored for a Sabres team that was outshot 15-4 in the second period and 28-24 overall. Buffalo came out flat and played sloppily, in part the result of playing games on consecutive nights following a 2-1 win at Chicago on Wednesday.
The Sabres (31-10-3) continue to struggle against Canadian teams based in their Northeast Division. Of Buffalo's 10 losses that have come in regulation, seven have been against Canadian division opponents, including Toronto twice.