Andy roddick
Del Potro and Monaco shoulder Argentina hopes
Argentina will start as favourites in their Davis Cup semi-final against the Czech Republic.
Victoria Azarenka survived a ferocious comeback from Sam Stosur to reach the US Open semi-finals.
Novak Djokovic continued his stroll through the US Open draw on Sunday.
Andy Roddick will fight to extend his career at the US Open on Sunday.
Andy Roddick has announced his retirement from professional tennis.
World number one Roger Federer needed just 62 minutes to beat 19-year-old Australian Bernard Tomic.
Jo-Wilfried Tsonga beat Milos Raonic in the longest three-set match in Olympic history.