Big three set for showdown in battle for Olympic tennis gold

(CNN) -- Roger Federer remained on course to complete a career golden grand slam after brushing aside John Isner of the United States in the quarterfinals Thursday. Federer, desperate to add Olympic singles gold to his 17 grand slam titles, struggled to cope with the giant Isner's service but still emerged as a 6-4 7-6 winner on Centre Court. A break in the 10th game of the first set gave the Swiss maestro the early advantage, but he was pushed all the way in the second. It went to a tiebreak where a fortuitous net cord for Federer gave the 17-time grand slam champion his passage to the last four. Flyover: Wimbledon Tennis Club Flyover: Wimbledon Tennis Club He will now face Juan Martin del Potro of Argentina after the former U.S. Open champion beat Japan's Kei Nishikori 6-4 7-6. Only Andre Agassi and Rafael Nadal have achieved the feat of claiming a full set of grand slam titles and backed it it with Olympic gold in the singles. Federer beat Britain's Andy Murray to win the Wimbledon crown last month and return to top spot in the world rankings.