Injury ends Wozniacki's New Haven run

Maria Kirilenko will meet Petra Kvitova in the final of the New Haven Open after Caroline Wozniacki pulled up injured against the Russian and the Czech second seed downed Sara Errani.

Four-times champion Wozniacki's winning streak at Yale came to an abrupt end when she was forced to retire midway through her semi-final with Kirilenko, the Dane citing a knee injury.

The former world number one had just dropped the first set 7-5 when she called the trainer and threw in the towel.

"I could feel it from the start," said Wozniacki, who picked up the knock in her quarter-final against Dominika Cibulkova.

"But, you know, it just started to get a bit worse. I decided to stop because if you don't feel a hundred percent, you can't compete at a hundred per cent.

"It's better to let it rest. I wasn't going to win this match anyways if I'm not on a hundred percent fit level."

Wozniacki had previously won each of the 20 matches she had played at the pre-US Open warm-up tournament. 

Seventh-seeded Kirilenko will face Kvitova for the title after the world number five eased past Italy's Errani 6-1 6-3.

The powerful Czech blitzed the fourth seed in an opening set that lasted just 24 minutes before breaking early in the second and never looking back.

"The run that I have here in North America, it's the first one," Kvitova said. "I didn't have a great result before, so I'm really glad for it."

The US Open starts in New York on Monday.