Shame he couldn't do more with it. He's won 7 titles with only 1 (2010 Barcelona) above 250 level. The highlight of his career was his epic semi-final battle with Nadal at 2009 Australian Open when he was a top 10 player (ranked as high as #7) and many tennis commentators thought he was about to join the then Big 4 (Federer, Nadal, Djokovic, Murray) to make a Big 5 but it never transpired. He seemed to fizzle out after that with just occasional flashes of his best form (he had another memorable quarter-final battle with Murray at 2013 Wimbledon. As at 2009 AO, he lost out to the eventual champion).
Undoubtedly one of the biggest ever under-achievers in men's tennis.