Vaclav Prospal had the other goal for Tampa Bay (38-27-4), which moved into a first-place tie with Atlanta atop the Southeast Division.
Ladislav Smid had the lone goal for Edmonton (30-31-6), which has lost five straight overall and four consecutive games since dealing forward Ryan Smyth to the New York Islanders at the NHL trade deadline.
Edmonton had the better quality chances in the scoreless first period, the best coming with seven minutes left when Petr Sykora hit the post on a shot.
Tampa Bay opened the scoring at 10:49 of the second when Brad Richards spotted Prospal in the slot on the power play and Prospal beat Edmonton netminder Jussi Markkanen. The Lightning led 2-0 less than three minutes later as Prospal took the puck behind the Oilers net and found an open Lecavalier, who scored his 44th goal of the season.
The Oilers broke Lightning goalie Marc Denis' shutout bid with just 2:35 left to play when Smid scored just his second of the season.
Lecavalier rounded out the scoring with an empty-net goal with 39 seconds left.
The Oilers begin a three-game road trip in Anaheim on Friday while the Lightning head to Calgary on Saturday for the fifth game of a season-high six-game road swing.
NOTES: With eight players out due to injury, the Oilers have had a regular pipeline of players coming up from the farm. The latest to receive a callup is St. Paul, Alta., native Kyle Brodziak. The 22-year-old had 21 goals and 46 points in 49 games with the AHL's Wilkes-Barre/Scranton Penguins and started the game on Edmonton's top line with Shawn Horcoff and Raffi Torres . . . The news didn't get any better on the injury front for Edmonton as defencemen Steve Staios (knee) and Jan Hejda (shoulder) left the game and did not return . . . Tampa Bay didn't emerge unscathed either as defenceman Paul Ranger left with a left knee injury . . . Despite the backlash against the Oilers in the wake of Smyth deal, fans are still coming out. Wednesday's game was the 67th consecutive regular-season sellout at Rexall Place . . . Tampa Bay is an impressive 15-0 when Richards has two or more points in a game.