"That was my first short-handed goal at any level of hockey," Vanek said. "It was good."
Buffalo coach Lindy Ruff said he made a deal with Vanek before the season started.
"I told him if he worked hard and kept his legs moving, he would see penalty-killing time," Ruff said. "My goal is to make him the best two-way player in hockey, and he has the potential to do that."
Ales Kotalik and Jason Pominville each had a goal and two assists. Jochen Hecht, Adam Mair and Clarke MacArthur also scored for the Sabres, who are 2-0-0 to start the season. Three of Buffalo's goals came on the power play.
Patrick Lalime got the start instead of Ryan Miller and made 23 saves.
"I knew two days ago I was starting today," Lalime said.
"It's nice to get in there, and when I get the call, I'll make the best of it."
Trent Hunter scored for New York.
The Islanders allowed 11 power plays to Buffalo.
"We were looking for the easy way," captain Bill Guerin said.
"That's why we took penalties. We can't take shortcuts."
Joey MacDonald started his third consecutive game for the Islanders. Top goalie Rick DiPietro was again on the bench as the backup. MacDonald stopped 28 shots.
Hecht scored on the power play to give the Sabres a 1-0 lead 10:09 into the game. Behind the net, Hecht threw the puck off MacDonald's stick, and it deflected into the net.
Hecht was injured later in the game.
Ruff said, "it's an upper-body injury, and he'll be reevaluated tomorrow."
Buffalo scored four times in the second period to take a 5-0 lead.
The Sabres upped their lead to 2-0 when Mair put home a rebound between MacDonald's pads at 2:22.
Vanek put Buffalo ahead by three at 7:00 with a short-handed goal.
"I think after the short-handed goal, we really took control of the game," Lalime said.
Just 99 seconds later, Pominville scored off a rebound for a 4-0 lead.
Vanek scored his second of the game at 10:32 on a power play.
Kotalik connected on a slap shot while the Sabres had a two-man advantage 58 seconds into the final period.
Lalime lost his bid for his 36th career shutout when Hunter put a slap shot past him on the short side at 5:21.
MacArthur tapped in a centering pass at 9:12 for his first of the season.
Outside of an injury, Islanders coach Scott Gordon was not pulling MacDonald.
"I can tell you right now, I'm not a strong believer in pulling our goalie to change momentum," Gordon said. "I don't want them looking over their shoulder to the bench. It's a way for Joey to find a way to battle, whatever the situation."
Notes: Islanders defenseman Radek Martinek, injured during Saturday's win vs. St. Louis, did not dress. ... The Islanders chose to wear their white jerseys for the home game. Last season, they wore the whites at home twice, and split the two games.
