After Victoria Azarenka won Brisbane, she withdrew from Sydney because of a viral illness. She thought she had totally recovered from it, but it appears that it hit her again at the worst possible time--right after she won the first set in her round of 16 match against Serena Williams. Azarenka tried to play the second set, but she appeared weak and dazed. I thought it was heat illness, but then I was reminded of the viral illness. Azarenka's immune system was recently compromised, and a combination of extreme heat and stress can easily cause a virus to return.
However, it turns out that it was food poisoning that took Azarenka down. She was vomiting early in the morning, but felt better later. After she won the first set, she looked very faint. She took a medical break, but looked none the better for it on her return to the court. By the time she retired, the people in her box--not to mention the rest of us--were concerned about her. I thought she was going to topple right over on the court.
It was a sad ending to what should have been a great match. With a retirement victory of 3-6, 4-2, Serena Williams moves to the quarterfinals.