Del Potro claims nervy ATP win

Juan Martin del Potro boosted his hopes of qualifying for the semi-finals of the Barclays ATP World Tour Finals at London's O2 Arena today with a nervy 6-4 3-6 7-6 (7/1) victory over Fernando Verdasco in this afternoon's Group A clash.

With both players having lost their opening match - Del Potro to Andy Murray and Verdasco to Roger Federer - they knew this contest could make or break their chances.

Despite failing to serve out the victory, it was the US Open champion who eventually came out on top, meaning Murray can book his place in the last four with victory against Federer this evening.

Verdasco had played superbly for two sets against the world number one on Sunday but it could not have been more different today, the Spaniard amassing 11 unforced errors in the opening five games.

Three of those came in the third game and allowed Del Potro to secure the first break of serve.

The world number five was erratic against Murray but the power generated by his extra height kept Verdasco largely at bay throughout a first set that only really came to life in the 10th game.

With Del Potro serving for a one-set lead, his opponent suddenly found his range and the Argentinian needed two pinpoint aces to save break points before a Verdasco backhand dropped wide on the second set point.

The initial stages of the second set, although of a better quality, were dominated by serve, but it was Del Potro who cracked first, Verdasco taking the first break point of the set.

That left the world number eight serving to level proceedings, and he completed the task with aplomb, wrapping up a love game with an ace.

Perhaps realising he had let his opponent into the match, Del Potro upped the ante at the start of the decider.

Verdasco resisted the pressure initially but in the sixth game an inopportune double fault gave his opponent three break points. Two were saved then on the third Del Potro stopped the rally to challenge a shot he thought had gone long.

He held his head in his hands awaiting the replay but the ball had indeed missed the line and the Argentinian had the breakthrough.

Verdasco was now on the ropes and he needed a brilliant pass to save a match point at 2-5 - and that would prove crucial moments later when Del Potro tamely surrendered his serve.

The 21-year-old had another match point at 5-4 but again it went begging and a tie-break was needed to separate them. This time Del Potro was not to be denied, though, and he wrapped up victory when Verdasco fired a forlorn forehand well wide.

Del Potro, who went out in the group stages of the tournament on his debut last year, admitted the nerves got to him at the end of the third set but was pleased he managed to come through.

The 21-year-old said: "I was very focused in the important moments, especially in the tie-break. And I took my opportunities. I felt nervous because, if I lose, I go home. But it's important, the victory of today, to get confidence."

Verdasco, who is making his debut at the end-of-season tournament, was disappointed to have lost another match he came close to winning.

He said: "I tried my best and I was really close.

"It was a big opportunity. But it's not enough to play good tennis to beat these guys. You need to play good tennis and also play very well in the very important moments and not to make mistakes.

"I was pretty close both days but the level of my tennis I think was good. I need to be happy for the level I played, but also at the same time I'm sad because I lost the matches."

Verdasco must hope Federer wins tonight and then must beat Murray on Thursday to have any chance of progressing, but he admits he is not holding out much hope.

"Right now the chances are pretty low," he added. "Many things need to happen for me to qualify."