For world time trial champion Tony Martin, bidding for Olympic gold risks being a painful experience -- especially with the prospect of a Bradley Wiggins triumph lurking in the background. German specialist Martin succeeded four-time world champion Fabian Cancellara of Switzerland in Copenhagen last year to claim a first, coveted rainbow jersey in the race against the clock. In normal circumstances the 27-year-old from Cottbus would start the 44 km time trial around Hampton Court Palace on Wednesday virtually assured of a medal. But more crash misfortune, and the emergence of Wiggins, has left Martin less sure of his chances. "There's just one name and it's Bradley Wiggins. He's the one to beat," said Martin. While the 2012 Tour de France smiled kindly on Wiggins, who brought home an historic yellow jersey, it was less happy for Martin.Having just recovered from facial fractures suffered in a training ride crash with a car in April, Martin suffered a fractured scaphoid bone in his wrist during a crash on the first stage of the Tour. The German battled on, but pulled out on the race's first rest day after finishing over two minutes behind Wiggins in the stage nine time trial. Like Cancellara, who only confirmed his participation on Monday following a crash in the men's road race, Martin is still in pain. He hopes adopting the time trial position with his forearms taking the pressure of his body leaning forward won't leave him in pain on the course's "quite bad" road surface. "The surface of the road on the course is quite bad but I don't think that's too big a problem, because I'm leaning forward and will be resting on my arms," Martin added. After Wiggins cruised triumphantly over distances of 41.5 km and 53.5 km to win twice on the Tour, Martin's confidence is subdued. "My goal for Wednesday is still a medal. I still hope for gold, but I don't have much hope left," he added. Wiggins, meanwhile, is confident of winning a fourth Olympic gold but his first on the road having won three from the pursuit events in his previous life as a track cyclist. "I've also got a chance to go for my fourth gold medal in the time trial," said the Briton, a month before his triumphant Tour campaign. Winning a fourth gold would put Wiggins on an Olympic medal tally of seven -- more than any other British Olympian. Former rower Sir Steve Redgrave has six, including five golds. Martin believes riding at home will only spur the Londoner on. "I think the expectation of the nation on Wiggins will be a motivating factor for him, not a handicap," he added. Like Martin, Cancellara's bid to defend the crown he won in Beijing four years ago will also be kept in check by medicinal limitations -- and the strict rules of the World Anti-Doping Agency (WADA). Swiss team doctor Andreas Goesele said: "He will have to ride with a higher level of pain than you or I, because we have to follow very precisely the WADA list (of prohibited substances). "The WADA list is very strict and we have to stick to it absolutely."