Shanghai, Nov 13: America's Andy Roddick pulled out of the Tennis Masters Cup with an ankle injury shortly before his group match with Roger Federer on Wednesday.
Roddick said he rolled his right ankle in training and would be out for about a week. He joins Rafael Nadal on the sidelines of the $4.45 million tournament after the world number one pulled out with knee tendinitis.
"Yesterday in the warm-up during practice I just went over on it," Roddick said.
"We tried the best we could to get it better but I can't really stop and start on it very quickly."
The sixth-ranked Roddick, who lost his opening match against Britain's Andy Murray, will be replaced by first alternate Radek Stepanek of the Czech Republic.
Stepanek, the world number 27, needs to beat Federer later on Wednesday and Gilles Simon on Friday to have any chance of qualifying for the semi-finals.