Thomas Vanek and Drew Stafford had a goal and assist each for Buffalo in a game the Islanders made close by scoring three times in the final period. Jason Pominville added three assists in helping the Sabres (50-20-7) become the first team to reach the 50-win plateau this season and gain sole possession of first place in the NHL standings.
With 107 points, Buffalo moved one ahead of Detroit in the league race, following the Red Wings' 4-3 shootout loss to Dallas.
Viktor Kozlov scored twice, including a goal in the final minute, and Tom Poti and Jason Blake added a goal each for the injury-depleted Islanders (36-29-12), who dropped to 2-5-2 in their past nine. They're struggling to remain in the playoff hunt entering the final week of the season.
Besides missing starting goalie Rick DiPietro (concussion) for a second straight game, New York was also minus high-scoring left-wing Ryan Smyth, who's listed day-to-day because of a leg injury.
Smyth has four goals and nine assists in 13 games with New York since being acquired from Edmonton at the NHL trade deadline last month.