Gauff beats Kostyuk but misses semifinals
Earlier, Gauff rallied to beat Kostyuk 6-4, 7-5 on Stadium Two at Indian Wells. Gauff rallied from 5-1 down in the second set, winning six consecutive games.
"I was fully prepared to play a third set there," said Gauff, who needed treatment on her back during the second set. "It's the last tournament of the season so I just wanted to finish it on a high note and give myself the best chance to play the semi-finals. Either way, I didn't want to be sad walking off the court."
Kostyuk joined the eight-player tournament as an alternate after world No 1 Elena Rybakina withdrew due to illness, but failed to win a set in her three matches as she struggled with a wrist injury.