Andy Roddick reached the second round of the Shanghai Masters after Philipp Kohlschreiber of Germany retired ill on Tuesday.
Kohlschreiber stopped while trailing 6-3, 2-1 after missing an easy overhead, shanking a forehand wide, and double-faulting to drop his serve.
Roddick, in and out of the top-10 rankings for the last two months, is looking to finish the year on a high and in the top 10 for a ninth consecutive season.
He reached the Japan quarterfinals last week, his first tournament since an early exit at the U.S. Open.
''I thought I hit the ball well in what we did play today. I started to hit the ball pretty well last week, also,'' Roddick said. ''I don't feel like I'm fighting myself out there. After the Open, I was able to train the way I want to for the first time in a while.''
Fellow American John Isner fought off match points in the two tiebreakers to beat Polish qualifier Lukasz Kubot 4-6, 7-6 (9), 7-6 (7) in 2 hours, 50 minutes. Isner served 24 aces, but failed to break Kubot once.
Next up for Isner is third-seeded Roger Federer, who received a bye in the first round.
Chinese wild card Yan Bai, ranked 465th, upset 30th-ranked Radek Stepanek of the Czech Republic 6-3, 6-4 for his first win on the main tour.
Yan lined up fourth-seeded Andy Murray in the second round.
''I have some pressure, of course, because this is my home country,'' Yan said. ''(Murray) is a very talented player - much better than me. I hope to learn from him in our match.''
