Wozniacki retires, Kirilenko reaches New Haven final

Four-time reigning champion Caroline Wozniacki was trailing Russian Maria Kirilenko on Friday when the former world No. 1 star retired at the New Haven Open at Yale, a final U.S. Open tune-up.

The seventh-seeded Kirilenko took the first set from the third-seeded Wozniacki, 7-5, when the Dane quit due to a right knee injury. The U.S. Open, where Wozniacki was a runner-up in 2009, starts on Monday.

The 14th-ranked Kirilenko had never beaten Wozniacki on the WTA (1-5).

Wozniacki is now 20-1 at the Connecticut Tennis Center at Yale, where she had never lost until Friday. She beat Czech Petra Cetkovska in last year's New Haven finale.

Kirilenko will now appear in her first-ever final in North America. Her opponent in Saturday's final will be second-seeded 2011 Wimbledon champ Petra Kvitova or fourth-seeded 2012 French Open runner-up Sara Errani. Kvitova has already clinched the top spot in the U.S. Open Series standings and will receive a $1 million bonus on top of her prize money at the final major of the year. A runner-up finish at the U.S. Open would earn her an extra $500,000.

The 25-year-old Kirilenko is 5-5 in her career finals, including a loss in Pattaya City earlier this season. The Russian glamour girl hasn't secured a WTA title since 2008, a year in which she tallied three championships on the circuit.

Kirilenko lost to world No. 1 Victoria Azarenka in the bronze-medal match at the London Olympic Games earlier this month.

The winner of this $637,000 event will pocket $107,000.