Viktor Troicki won his rain-delayed quarterfinal at the Sydney International on Friday, and Australian Bernard Tomic retired from his match against Russian Teymuraz Gabashvili while trailing 6-3, 3-0.
Tomic said he was feeling ill and may have had food poisoning. He plays his first-round match at the Australian Open in Melbourne on Tuesday against Uzbekistan's Denis Istomin.
Rain had postponed Tomic's quarterfinal until Friday morning, meaning he would have been forced to play a second match later in the day had he advanced to the semifinals.
"I was just feeling a little bit sick last night and was very difficult to play two matches today," Tomic said.
Third-seeded Troicki beat Nicolas Mahut 4-6, 6-3, 6-3 and will play Gabashvili later on Friday for a spot in Saturday's final.
Fourth-seeded Grigor Dimitrov advanced with a 4-6, 6-3, 6-4 quarterfinal win over Alexandr Dolgopolov and will next play Gilles Muller, who beat sixth-seeded Jeremy Chardy of France 7-6 (5), 6-3.
In the women's semifinals at Sydney, two-time Grand Slam champion Svetlana Kuznetsova beat top-seeded Simona Halep 7-6 (5), 4-6, 6-3. Kuznetsova's final opponent will be Monica Puig, who advanced when Belinda Bencic retired ill after losing the first set 6-0.