Roddick's hopes fade after Berdych defeat

Andy Roddick's hopes of reaching the semi-finals of the ATP World Tour Finals were hanging by a thread on Wednesday as the American was beaten 7-5, 6-3 by revived Czech Tomas Berdych at the O2 Arena.

A second consecutive defeat for Roddick after his three-set thriller against Rafael Nadal on Monday means he could be eliminated if Novak Djokovic beats world number one Rafael Nadal in the later Group A match.

Wimbledon runner-up Berdych, who was disappointing against Djokovic on Monday, saved two set points at 4-5 in the first set and that proved to be a pivotal moment as the confidence that has been missing of late came flooding back.

He earned his first break point on the Roddick serve in the following game and converted it in ruthless fashion when he smacked a 110mph second serve straight back past his motionless opponent with a rasping forehand.

Berdych held serve to move a set ahead and Roddick was left smashing his racket in frustration when he dropped serve again at 2-2 in the second -- missing the sideline by a fraction with a smash after a superb defensive lob by Berdych.

World number eight Roddick never regained his composure and serving at 3-5 he pulled a limp forehand into the net on match point down to hand tournament debutant Berdych, who had managed just eight wins since losing to Nadal in the Wimbledon final in July, a morale-boosting victory.

Djokovic can become the first player in the eight-man event to reach the semi-finals if he beats Nadal later.

World number two Roger Federer leads Group B with two victories from Robin Soderling and Andy Murray, who both have one apiece.

The top two places in that group will be decided on Thursday when Federer plays Soderling and Murray takes on Spain's David Ferrer.