Winston-Salem, United States: Two-time champion John Isner withdrew from the US Open tune-up event at Winston-Salem on Thursday with a left ankle injury.
The American was due to play Lukas Rosol in the quarter-finals on Thursday, but pulled out with the injury suffered in his win over Mikhail Kukushkin on Wednesday.
“I am extremely disappointed to have to withdraw from the Winston-Salem Open, one of my favourite stops of the year,” said Isner, who hails from North Carolina.
It wasn’t yet clear if the injury would affect 29-year-old Isner’s appearance in the US Open, which starts on Monday in New York.
Isner is seeded 13th at the Open, and according to the draw released on Thursday could face top seed Novak Djokovic in the fourth round.
Rosol advanced by walkover into a Friday semi-final against Taiwan’s Lu Yen-Hsun, who defeated Italy’s Andreas Seppi 6-4, 6-4.
The other semi-final will match Poland’s Jerzy Janowicz, who ousted Belgian David Goffin 6-4, 6-2, against American Sam Querrey, who rallied to eliminate Spanish fifth seed Guillermo Garcia-Lopez6-7 (3/7), 6-2, 6-4.
Meanwhile, reigning Wimbledon champion Petra Kvitova advanced to the semi-finals of the WTA New Haven hardcourt tournament Thursday with a 6-4, 6-1 triumph over Czech compatriot Barbora Zahlavova Strycova.
Fourth-ranked Kvitova next will face Australia’s Samantha Stosur, who ousted Belgium’s Kirsten Flipkens 6-3, 4-6, 6-3 in the final warm-up event for the US Open, which begins Monday.
Second seed Kvitova, the 2012 New Haven winner who lost to Simona Halep in last year’s final, will be the third seed at the year’s last Grand Slam event and will open her Flushing Meadows fortnight next week against France’s 73rd-ranked Kristina Mladenovic.
Kvitova, a 24-year-old left-hander, won their first meeting in 2008 at Paris but lost to Mladenovic, 21, last year in Paris.
Slovakia’s Magdalena Rybarikova defeated American Alison Riske 7-5, 0-6, 6-4 to book a semi-final berth against Italy’s Camila Giorgi, who defeated Spain’s Garbine Muguruza 6-4, 6-7 (4/7) 6-2.
Giorgi ousted four-time New Haven champion Caroline Wozniacki, the Danish fourth seed and former world number one, in the second round.
