CHENNAI, India (AP) - 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.
Wawrinka defeated Benjamin Becker of Germany 6-3, 6-1, while Youzhny retired ill against Dudi Sela of Israel while trailing 3-1 after 24 minutes.
''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 and I was really happy with my performance today. I think I did a really, really good job. It's quite slow and humid out there and it was raining a bit.''
Youzhny's compatriot, Alexander Kudryavtsev, also retired while leading 6-1, 0-3 against Aljaz Bedene of Slovenia.
Kudryavtsev, who knocked out eighth-seeded Roberto Bautista Agut of Spain in the first round, suffered a leg injury.
Seventh-seeded Frenchman Edouard Roger-Vasselin also defeated Jiri Vesely of the Czech Republic 6-4, 6-4.