Roddick pulls out of Masters Cup

Roddick will not be showing off his talents in Shangai

Andy Roddick has withdrawn from the Masters Cup in Shanghai because of an injury to his right ankle.

The American was due to play defending champion Roger Federer in his Red Group match on Wednesday but picked up the injury during practice on Tuesday.

World number 27 Radek Stepanek of Czech Republic replaced Roddick and was beaten 7-6 (7-4) 6-4 by the Swiss.

Roddick, seeded fifth in the eight-man draw, lost his opening match to British number one Andy Murray on Monday.

"The injury was during a warm-up drill in practice yesterday," Roddick said.

"I can't really stop or start quickly. It's definitely a tough prospect trying to beat Roger and not being able to move much."

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After finishing in the world's top 10 for the seventh consecutive season, Roddick does not expect his preparations for next year to be hampered with the Australian Open starting on 19 January.

"They don't think it's too long term, which is nice," he added. "It's unfortunate for this event as far as I go, but I don't think we're looking at anything more than a week or so.

"Which in the grand scheme of things is good news considering the nature of the injury."