After two games where most of the offence came from the defence, Vanek, Daniel Briere, and Adam Mair all scored second-period goals to earn Buffalo to a 3-2 victory over the New York Islanders and a 2-1 lead in the first-round, Eastern Conference playoff series.
The Sabres, who led the NHL with 308 goals, scored six while splitting the first two games on home ice. Chris Drury, who assisted on Mair's goal, scored twice in the series-opening victory for the only goals by Buffalo forwards.
That all changed when the Sabres scored three times in a span of 7:39.
Trent Hunter and Ryan Smyth answered in the second in front of a towel-waving, sellout crowd that included NHL commissioner Gary Bettman. It wasn't enough, despite 32 saves by Rick DiPietro in his first home game in three weeks following a bout with post-concussion syndrome.
When Randy Robitaille was whistled for tripping with 1:34 left, the white towels stopped waving and came flying down to the ice, along with other debris.
Game 4 of the best-of-seven series is here Wednesday. Game 5 is back in Buffalo on Friday.
Ryan Miller recovered from a shaky start to make 20 saves in his second career playoff victory.
After a lacklustre first in which Buffalo was outshot 10-9, the speedy Sabres quickly took the play to the Islanders in the second. With constant pressure and long-term puck possession in the New York zone, Mair made it pay off at 5:17.
Hunter got knocked off the puck on the offensive end, and defenceman Henrik Tallinder rushed back up ice. He gave the puck to Drury, who crouched to make a precision cross-ice pass from above the left circle to Mair. He easily steered the puck in as he raced toward the left post.
By then, Buffalo had a 4-0 shots advantage in the period. New York wouldn't record a drive until Richard Zednik's shot after 6:03 elapsed.
Vanek, who had a Sabres-high 43 goals this year, had to sweat out a video replay before being credited with a goal at 8:38. He curled around from behind the net and jammed the puck at the left post as DiPietro tried to keep his skate in the way.
Vanek stumbled into the middle of the Islanders' zone and celebrated what he felt was a sure goal as the puck was still loose in the crease. The goal light never turned on, and a lengthy video review ensued. Fans, who had chanted, "No goal, no goal," changed their pleas to groans when the goal was awarded.
Miller shook off a tough first in which he was twice staggered by shots squarely off his mask to make eight stops in the second.
He was beaten by Hunter 1:14 after Vanek's goal, snapping New York's home playoff scoreless streak at 187 minutes four seconds, dating to Adrian Aucoin's goal in Game 4 against Ottawa exactly four years earlier.
Penalties did in the Islanders with just over eight minutes left in the period when Tom Poti was called for a double high-sticking penalty at the same time Marc-Andre Bergeron was whistled for slashing.
That gave Buffalo a 5-on-3 advantage and put two of the Islanders' six defencemen in the penalty box.
It became too much to overcome.
Tim Connolly's pass in front was blocked by New York's Brendan Witt, but Briere found the loose puck to DiPietro's right and lifted a shot under the crossbar to make it 3-1 with 7:04 left in the period.
It appeared the Sabres would carry a two-goal lead into the third, but Smyth scored with only eight seconds left to cut New York's deficit to 3-2.
Notes: A moment of silence was held for the victims of the shooting at Virginia Tech earlier in the day. ... New York was shut out twice at home by Tampa Bay in 2004, the last time the Islanders qualified for the postseason. ... Briere had a team-high 95 points in the regular season. ... Islanders captain Alexei Yashin, who played a team-low seven minutes in Game 2, was relegated to the fourth line and power-play specialist.