Juan Martin del Potro edges a tight first set in his clash with France's Jo-Wilfried Tsonga in the second round of matches in the Gold Group

Both players need wins after losing their opening matches and Tsonga shows his frustration after a series of errors in the second set

It is Del Potro who eventually triumphs - winning two close sets on tie-breaks - to keep his hopes of reaching the semi-finals alive

Novak Djokovic is going for his second group win when he takes on Nikolay Davydenko and edges the first set on a tie-break

But Davydenko's relentless style blows the Serbian away in the second set - winning it 6-0 - to take the match into a decider

The third set is a tight one and goes with serve to 5-5. A couple of bad errors from Davydenko and Djokovic secures his semi-final spot