Sydney - Defending women's champion Petra Kvitova has withdrawn from the Sydney International, marking the second consecutive week that the two-time Wimbledon winner has pulled out of tournaments due to a lingering stomach virus.
Kvitova retired during the first round of the Shenzhen Open in China last week. She was scheduled to play her first match in Sydney against Germany's Sabine Lisicki on Monday.
"I'm really disappointed to have to withdraw ... but unfortunately I am still not feeling well," Kvitova said in a statement Sunday.
Bernard Tomic is the top-seeded man at Sydney, while Simona Halep and Agnieszka Radwanska are the top-seeded women.
In first-round WTA matches Sunday, former French and U.S. Open champion Svetlana Kuznetsova beat Australian Tammi Patterson 6-2, 6-0 and Tsvetana Pironkova of Bulgaria defeated Lesia Tsurenko of Ukraine 7-6 (6), 6-2.
Ana Ivanovic, who received a wild card, was scheduled to play her first-round match later Sunday against fifth-seeded Karolina Pliskova.
At the Hobart International, another of the Australian Open warm-up tournaments, seventh-seeded Alize Cornet of France beat Denisa Allertova of Czech Republic 6-4, 7-5 and Russian Margarita Gasparyan defeated 17-year-old Australian Maddison Inglis 6-4, 6-3.
Sloane Stephens, who won the ASB Classic in Auckland on Saturday, was a late withdrawal from Hobart due to a virus.
Former No. 5 Eugenie Bouchard, who is entered at Hobart, says she has "zero expectations" to perform at the Australian Open as she makes her comeback from a concussion she sustained at the U.S. Open when she slipped and fell in the dressing room.
The Canadian made the quarterfinals at last week's Shenzhen Open after a four-month layoff.
"A month or two ago I wasn't even sure I could play the Australian Open, so I'm just so happy to be in Australia, looking forward to playing these two tournaments (with) zero expectations," the 21-year-old Bouchard said Sunday.
She was pleased with her play in China despite losing in the final eight to Hungarian Timea Babos.
"To step on the court and play a full match with no pain, play three matches three days in a row, was a success for me even though I lost the last match," she said.
Bouchard will play American veteran Bethanie Mattek-Sands in the first round in Hobart, likely on Monday.
Last week, the world's four top-ranked women retired or withdrew from tournaments due to injuries on the left side of their bodies — No. 1 Serena Williams (knee), second-ranked Halep (Achilles), No. 3 Garbine Muguruza (foot) and fourth-ranked Maria Sharapova (forearm). Radwanska is ranked fifth and Kvitova sixth.
The Australian Open begins Jan. 18 in Melbourne.