Defending champion Petra Kvitova has been forced to pull out of the APIA International in Sydney due to a gastrointestinal illness.

โ€œI'm really disappointed to have to withdraw from the Apia Sydney International but unfortunately I am still not feeling well,โ€ said Kvitova.

โ€œBeing defending champion, this tournament obviously means a lot to me and I've always had a wonderful time playing this event.

โ€œI look forward to coming back in future years to play for my fantastic fans.โ€

Kvitova, the current world No.6, was due to face Sabine Lisicki in the opening round.