NEW YORK - Andy Roddick advanced to the third round of the US Open on Thursday when his Argentine opponent Jose Acasuso retired with a left knee injury at the end of the third set.
Although Acasuso had taken the first set, former champion Roddick looked in commandat two sets to one, leading 4-6 6-1 6-2 when the Argentine decided to quit.
World number 70 Acasuso startled Roddick early on but after the American hit back to level, the Argentine had his left knee strapped.
Roddick took advantage by cruising through the third set and, after consulting the trainer again, Acasuso decided he could not continue.
"It's unfortunate that Jose hurt his knee. I though he played a very good first set," Roddick said in a courtside interview.
"It's not the way you want to get through but at the beginning of the day all you want to do is get through to the third round.
"I felt like I started playing a lot better in the second set so hopefully I can carry that through into the next round."
Roddick, who was runner-up to Roger Federer last year, will play either Frenchman Arnaud Clement or former Australian Open champion Thomas Johansson of Sweden.
Also today, Andy Murray continued his recovery from a wrist injury by scrapping his way to a 5-7 6-3 6-1 4-6 6-1 victory over veteran Swede Jonas Bjorkman in the second round.
The 19th-seeded Scot, who returned earlier this month after 12 weeks out, needed three hours 37 minutes and 16 aces to clinch a meeting with 14th-seeded Argentine Guillermo Canas or Hyung-Taik Lee of South Korea.
Bjorkman, 35, the oldest man in the draw, took the first set before Murray, varying his pace well, rallied to take the second and third.
The Swede, a semi-finalist in 1997, snatched the fourth with his third break of the set but Murray broke three times in the decider to seal an energy-sapping victory.
