Los Angeles finally ended its nearly 7-minute scoreless drought and got the lead back up to 55-47 before New York scored 13 of the next 17 points to take its first lead of the game on two free throws by Ionescu with 1:14 left.
After a Los Angeles miss, Ionescu was fouled shooting a 3-pointer with 34.1 seconds left. She made two of three to give the Liberty a 62-59 advantage.
Jordin Canada was fouled driving to the basket and made both free throws to get the Sparks within one with 29.6 left.
After a timeout, Ionescu worked the clock down before driving into the lane and banking in a shot from the free throw line with 6.9 seconds left.
Los Angeles had one last chance but Lexie Brown missed a 3-pointer from the wing just before the buzzer.
Nneka Ogwumike scored 19 points to lead Los Angeles.
The Sparks jumped out to a 24-8 lead after the first quarter as Ogwumike scored seven points. She moved past Swin Cash for 20th on the league's all-time scoring list. Ogwumike has 5,137 points now in her career.
New York rallied to within seven late in the first half before Los Angeles scored the final four points to take an 11-point lead into the break.
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