Thornton’s wrist shot at 2:22 in the extra session gave the Sharks a 4-2 best-of-seven series victory over the Kings, after they had failed to eliminate their Pacific division rival in Game Five on Saturday.
San Jose goaltender Antti Niemi, who was pulled from the net in his previous start, made 26 saves for the Western Conference second seeds.
San Jose’s Kyle Wellwood scored the game’s opening goal in the second period. Both teams then traded goals through regulation with Justin Williams levelling at 1-1 before Jason Demers gave the Sharks a 2-1 lead with just over three minutes remaining in the period.
Ryan Smith tied the score at 2-2 less than 20 seconds into the third before Dany Heatley gave the Sharks the lead again with just over 11 minutes remaining.
Trevor Lewis, however, ensured the game went into overtime when he scored with a wrist shot at 11:39 in the third.
Jonathan Quick made 31 stops for Los Angeles one game after stopping a franchise playoff-record 51 shots but it was not enough to keep the Kings’ season going.
In Tampa Bay, the Lightning however staved off elimination when they beat the Pittsburgh Penguins 4-2 and forced a deciding Game Seven.
After routing the Penguins 8-2 on Saturday, the Lightning closed Monday’s game with third period goals from Steve Downie and Ryan Malone to snap a 2-2 tie and level the best-of-seven series at 3-3.
“It’s going to be fun,” Malone told reporters. “We worked hard to get to this point. We’re going to go in there, try to establish ourselves early and see what happens.”
The Penguins, who had held a 3-1 series lead despite the absence of injured forward Sidney Crosby and Evgeni Malkin, have been outmatched in the last two games as Tampa Bay has rediscovered its offensive spark.
Pascal Dupuis scored the opening goal of the game in the first for Pittsburgh while Jordan Staal tied the game at 2-2 in the third before the Lightning struck and seized the momentum ahead of the decider on Wednesday in Pittsburgh.
