CHENNAI, India -- Top-seeded Stanislas Wawrinka of Switzerland advanced comfortably but second-seeded Mikhail Youzhny of Russia quit during his second-round match due to a stomach infection in the Chennai Open on Wednesday.
"It's a stomach problem," Youzhny said. "I tried my best but it was not possible. When you have restricted movement, it's no use to play on center court and lose. It started last week in Thailand ... some virus ... and it continued here this week, too. I'm sorry for the tournament and the spectators."
Wawrinka said Youzhny's retirement would not make things easier for him.
"For me, it does not matter, because if it's not Youzhny, it will be someone else," Wawrinka said. "It's a good start. I think I did a really, really good job. It's quite slow and humid out there and it was raining a bit."
Kudryavtsev, who knocked out eighth-seeded Roberto Bautista Agut of Spain in the first round, suffered a leg injury.