Candace Parker scored with 5.7 seconds remaining in the second overtime to propel Los Angeles to a 90-88 victory and simultaneously hand Tulsa its most depressing loss of the season.
The Shock led by 19 points in the fourth quarter but couldn't hold off a furious rally by the Sparks. L.A. went on runs of 14-2 and 13-2 in the final quarter, outscoring Tulsa 29-10 overall in the fourth.
Tulsa had a chance to win until the bitter end, but watched as a Riquna Williams' 3-pointer rimmed out in the final seconds of double overtime.
Parker led the charge for L.A. with 26 points and 11 rebounds and also scored the game-winning basket on an uncontested layup to lift her team to 19-8 on the season and one game out of first place in the Western Conference standings.
The Sparks' comeback effort was aided when Tulsa's Liz Cambage was forced to leave the game with a sprained ankle with 6:35 remaining in the fourth quarter.
Candice Wiggins paced the Shock with 20 points and also forced the second overtime when she drained a 3-pointer with 7.9 seconds left.
Despite playing two overtimes, only two other Shock players reached double figures. Williams scored 17 on 6-of-16 shooting and Glory Johnson chipped in 11. Before Cambage left the game, she scored eight points and snagged a game-best 14 rebounds.
With the loss, Tulsa fell to 9-19 on the season. The Shock hosts San Antonio on Friday at 7 p.m.