INDIAN WELLS, California, Nov 10 - Jessica Pegula kept her hopes alive of reaching the semi-finals of the WTA Finals with a 6-2 7-5 victory over Marta Kostyuk on Tuesday, as Group 1 action continued at the season-ending tournament.

The American, who lost her opening match to compatriot Coco Gauff in three sets, responded with a composed performance to eliminate Kostyuk, who was a late addition to the draw after replacing world number one Elena Rybakina following the Kazakh's withdrawal through illness.

Pegula made an immediate statement, breaking Kostyuk in the opening game before securing another break to take the first set comfortably. She carried that momentum into the second, breaking again in the opening game, but the Ukrainian fought back as the pair exchanged breaks twice to remain level.

Kostyuk's resistance ultimately faltered, with Pegula finding another break late in the set before serving out the match.

The victory marked a turnaround for Pegula, following her opening defeat, and a particularly disappointing result for Kostyuk, who was eliminated from semi-final contention.

The world number 10 faced Pegula on a five-match losing streak and had been struggling with a right wrist injury that had troubled her since the hard-court swing.

Kostyuk had also beaten Pegula in both of their previous meetings this year, in Brisbane and Madrid, but was unable to reproduce that form. REUTERS