Andy Roddick takes on Tomas Berdych at the ATP World Finals later this afternoon.

It's the survival match in Group B as Roddick and Berdych bid to keep their hopes of reaching the semi-finals alive. They both suffered contrasting defeats on Monday as Berdych capitulated fairly tamely 6-3, 6-3 against Novak Djokovic amid a flood of unforced errors. Roddick matched Nadal shot for shot for more than two hours before eventually going down 3-6, 7-6, 6-4 in the match of the tournament to date.  

Roddick led by a set and a break at one point and the American was far from disheartened afterwards, knowing that if he maintains that form, his chances of qualifying from Group B are still good.

Tactically, Roddick has the more options of the two players. He's the better mover and has the ability to rush Berdych and cut off the rallies at the net. Berdych has greater brute power from the back of the court but it's a fairly slowish indoor court and his groundstrokes were all over the place in his opening match.

Roddick leads the head-to-head 6-2. They have had some close battles in 2010 but the American has come through all three of them, 1-6, 6-3, 6-4 in Brisbane, 7-6, 7-6 in San Jose and 7-5, 6-4 in the Miami final.

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Roddick v Berdych starts at 14.00 GMT