Petra Kvitova withdraws from WTA Championships

Defending champion Petra Kvitova has been forced to withdraw from the ongoing WTA Championships in Istanbul because of a viral illness.

The 22-year-old made the decision following her 6-3 6-2 defeat to Poland's Agnieszka Radwanska yesterday afternoon.

Despite having pulled out of the tournament, the Czech Republic's Fed Cup captain Petr Pala is hopeful that the former Wimbledon champion will be available for next month's clash with Serbia.

"She is a top player and, regardless of the WTA Championships, I'm convinced she is preparing well for the Fed Cup weekend," said Pala.

Kvitova's place in Turkey has gone to Australian Samantha Stosur.