Lecavalier showed what helped make him the top overall draft pick in 1998, beating goaltender Garth Snow with one-on-one moves to provide Tampa Bay with a 3-0 lead early in the second period.
Just 77 seconds into the second, Lecavalier scored his first career shorthanded goal.
Known more for his scoring punch than his punches, Lecavalier later fought tough guy Eric Cairns, although officials quickly jumped in to protect Tampa Bay's talented center.
Vaclav Prospal scored the decisive goal in the second period for the Lightning, who had not defeated the Islanders since March 3, 2001. New York had won three straight in Tampa Bay, including a 7-2 rout on Nov. 21.
Defenseman Dan Boyle had a pair of assists for the Lightning, who made a triumphant return from a 1-2
Defenseman Cory Sarich scored 12 seconds into the game for Tampa Bay, the second-fastest goal in franchise history. Dino Ciccarelli tallied 11 seconds into a game against Washington on Feb. 15, 1997.
Playing for the second time in as many nights in Florida, the Islanders got within a goal with 7:38 to play before falling to 3-2-1 in their last six games.