Novak Djokovic plays Andy Roddick in the final Group B match on Friday night at the Barclays ATP World Finals.

Djokovic will be hoping to put the disappointment of his loss to Nadal on Wednesday behind him and seal his place in the last four. The Serb played superbly to defeat Tomas Berdych in straight sets at the start of the week and he was matching Nadal shot for shot until a contact lens became dislodged and he was unable to regain his focus. Djokovic was pretty down afterwards but he knows that if he defeats Roddick then he has a great chance of qualifying unless Berdych pulls off something special against Nadal.

Roddick can count himself fairly unlucky this week. He came within a few points of defeating Nadal on Monday but just could not find the first serves at the crucial times and then ran into an inspired Berdych on Wednesday. However many pundits felt that Roddick was too passive against Berdych, particularly with his forehand and he needs to be prepared to take some risks to have a chance against Djokovic.

Roddick has the psychological edge going into this one as he leads the head-to-head 5-2. If Nadal beats Berdych in the afternoon as expected then the American still has a chance of qualifying. Roddick beat Djokovic at the Australian Open, Indian Wells and the Montreal Masters in 2009 and won 6-4, 7-5 when they met in Cincinnati back in the summer.