Vanek's 2 goals lift Sabres over Maple Leafs 5-4
Drew Stafford and Andrej Sekera also scored, and Ryan Miller made 29 saves for the Sabres (16-12-3), who won for the third time in six games.
Down by a goal midway through the second period, Buffalo scored three straight times -- including two power-play goals -- to take a 4-2 lead. Toronto committed five penalties in the second, and over the final 7:03 of the period the teams played 5-on-5 for just 6 seconds.
Nikolai Kulemin scored on a penalty shot in the third period, and Dion Phaneuf, Joffrey Lupul, and Mikhail Grabovski also scored for Toronto (16-12-3), which has dropped three of four (1-2-1).
Sekera's goal came with just under 2 minutes to go in the second, after Phaneuf was handed a 5-minute major for boarding and ejected for checking Zack Kassian into the end boards from behind.
James Reimer made 24 saves in his fourth straight start for the Maple Leafs, who had their three-game winning streak against Buffalo snapped.
Kulemin converted his penalty shot at 9:56 of the third after he was tripped by a sliding Jordan Leopold while on a breakaway to make it 4-3.
Vanek pushed Buffalo's lead to 5-3 with his second of the game at 15:44 of the third, but Grabovski made it 5-4 just 31 seconds later.
After a scoreless first period, the Maple Leafs struck first on Lupul's 14th goal 1:49 into the second. On a 2-on-1 rush with Phil Kessel, Lupul took Kessel's pass in the left circle before flicking the puck over Miller.
Stafford tied it 2 1-2 minutes later when he tapped in Vanek's pass in tight on the power play.
Toronto made it 2-1 on Phaneuf's power-play goal at 9:03 of the second, but Vanek tied it 19 seconds later when he wristed in a shot from the lower portion of the left circle for his 15th of the season.
Ennis gave the Sabres their first lead, 3-2, with a goal with just under 6 minutes left in the second with Buffalo on a two-man advantage.
NOTES: The Sabres recalled LW Colin Stuart from Rochester (AHL). ... Buffalo LW Ville Leino missed his first game and is out indefinitely after sustaining a lower body injury Tuesday against Ottawa. ... Buffalo is still without seven regulars. ... The teams will meet again in Toronto on Thursday. ... Vanek and Sabres C Derek Roy played in their 500th NHL game. ... Stafford's goal was his 100th in the NHL. ... Miller has stopped 12 of 14 penalty shots in his career. ... Toronto hadn't scored on a penalty shot since Dec. 26, 2006, when John Pohl connected against Minnesota.