New Haven, United States: Four-time champion Caroline Wozniacki and two-time defending champion Petra Kvitova on Thursday set up a mouthwatering semi-final showdown at the US Open tune-up event at New Haven.

Kvitova, the second seed, rallied from 5-3 down in the opening set to beat seventh-seeded Agnieszka Radwanska of Poland 7-5, 6-4.

Denmark’s Wozniacki, seeded third, overcame an early break of serve, winning 11 of the next 13 games in an emphatic 6-3, 6-0 victory over France’s Caroline Garcia.

Wozniacki, who has been troubled by back and calf injuries this season, did much of her damage with an unexpected barrage of forehand winners.

The convincing victory was a welcome respite after the 2014 US Open runner-up had to save three match points in a second-round win over Italian qualifier Roberta Vinci.

But Wozniacki will face a stiff test in the semi-finals against Kvitova, as both seek a morale-boosting win ahead of the final Grand Slam of the season, which starts on Monday at Flushing Meadows.

“I really needed this win and finally I played two sets, so that’s good as well,” said Kvitova, who took time off this season because of exhaustion and later revealed she had battled glandular fever.

Lucky loser Lesia Tsurenko continued to make the most of her good fortune, booking a semi-final berth with a 6-2, 6-2 victory over fifth-seeded Czech Karolina Pliskova.

Ukraine’s Tsurenko gained a place in the draw - and a first-round bye - when top-seeded Romanian Simona Halep withdrew from the tournament.

She has since defeated Czech Barbora Strycova and Pliskova, and will try to see off another Czech when she next faces fourth-seeded Lucie Safarova, a 6-7 (4/7), 6-4, 7-5 winner over Slovakia’s Dominika Cibulkova.