Novak Djokovic (R) of Serbia retires from his match against Andy Roddick of the US during their men’s singles tennis match on day 9 of the Australian Open in Melbourne on January 27, 2009. Roddick powered into the Australian Open semi-finals when defending champion Novak Djokovic pulled out with illness trailing 7-6 (7/3), 4-6, 2-6, 1-2. AFP PHOTO / GREG WOOD (Photo credit should read GREG WOOD/AFP/Getty Images)