World number one Roger Federer squeezed into the semifinals of the ATP World Tour Finals on Thursday despite a 6-2, 6-7(5), 6-3 defeat by Juan Martin del Potro and the result also knocked Andy Murray out of the tournament.

Del Potro and Federer both advanced after a three-way tie in Group A, with Murray's elimination literally coming down to the last game after three rounds of group matches.

All three players finished the round-robin stage with two wins and identical 5-4 set records, but Murray had the lowest percentage of games won. Had Del Potro lost just one more game against Federer, Murray would have advanced at the Argentine's expense.

Switzerland's Roger Federer reacts after missing a shot against Argentina's Juan Martin Del Potro during their ATP World Tour Finals tennis match at the 02 Arena in London November 26, 2009.

In an earlier match, Murray notched up a 6-4, 6-7(4), 7-6(3) victory over Spain's Fernando Verdasco.

"I'm going to go home, get some rest and then see what happens with the match. I definitely won't watch too much of it. Got to try and look after my body the best that I can, if I get to play another match," said the 22-year-old Scot.

Verdasco's defeat ended a miserable outing for Spain at the tournament. The country was the only nation to field two representatives in the elite eight-man line-up but both Verdasco and Rafael Nadal, who was in Group B, were eliminated.

Verdasco, 26, was the debutant at the season finale. He was close to winning all the three matches but came away with nothing.

"Of course it's tough when you play good and you lose. But you know, the positive thing is against the No. 1, 4 and 5 in the world, I was really close to win," said Verdasco.

"So that means that I have the level to win against these guys. I just need to improve a little bit more my tennis and maybe next year I will win these matches."

World number one Roger Federer squeezed into the semifinals of the ATP World Tour Finals on Thursday despite a 6-2, 6-7(5), 6-3 defeat by Juan Martin del Potro and the result also knocked Andy Murray out of the tournament.

Del Potro and Federer both advanced after a three-way tie in Group A, with Murray's elimination literally coming down to the last game after three rounds of group matches.

All three players finished the round-robin stage with two wins and identical 5-4 set records, but Murray had the lowest percentage of games won. Had Del Potro lost just one more game against Federer, Murray would have advanced at the Argentine's expense.

Switzerland's Roger Federer reacts after missing a shot against Argentina's Juan Martin Del Potro during their ATP World Tour Finals tennis match at the 02 Arena in London November 26, 2009.

In an earlier match, Murray notched up a 6-4, 6-7(4), 7-6(3) victory over Spain's Fernando Verdasco.

"I'm going to go home, get some rest and then see what happens with the match. I definitely won't watch too much of it. Got to try and look after my body the best that I can, if I get to play another match," said the 22-year-old Scot.

Verdasco's defeat ended a miserable outing for Spain at the tournament. The country was the only nation to field two representatives in the elite eight-man line-up but both Verdasco and Rafael Nadal, who was in Group B, were eliminated.

Verdasco, 26, was the debutant at the season finale. He was close to winning all the three matches but came away with nothing.

"Of course it's tough when you play good and you lose. But you know, the positive thing is against the No. 1, 4 and 5 in the world, I was really close to win," said Verdasco.

"So that means that I have the level to win against these guys. I just need to improve a little bit more my tennis and maybe next year I will win these matches."