LONDON, England (Reuters) – Roger Federer rebounded from a poor start to crush Andy Murray at the ATP World Tour Finals on Tuesday, claiming a 3-6, 6-3, 6-1 victory that ensures he will end the year as the world’s top ranked player for a fifth time.

His second round-robin victory at the season-ending showpiece in London’s space-age O2 Arena means Rafael Nadal can no longer prevent the Swiss joining Pete Sampras and Jimmy Connors as the only players to finish a year as number one five times or more since rankings were introduced in 1973.

It was not vintage Federer, especially in an error-strewn first set, but the 15-time grand slam champion dominated from then on, swarming all over a weary-looking Murray after breaking in the middle of the second set.

From 0-1 down in the third set Federer turned up the power on his forehand and romped through the next six games, treating the capacity 17 500 to some flashes of brilliance that make him one of the greatest attractions in world sport.

Federer, who had lost to Murray on six of their previous nine encounters, will face Juan Martin del Potro, the man who stunned him in the U.S. Open final in September, today, with his semi-final place still not secure.

Del Potro’s 6-4, 3-6, 7-6 victory over Spain’s Fernando Verdasco earlier in the day meant that all four players in Group A could still reach the semi-finals.

“I felt nervous because if I lost, I go home,” the 21-year-old Del Potro, who hopes to have Argentina striker Carlos Tevez watching against world number one Federer, told reporters.

“It was important, the victory today, to get confidence. I hope to play my best tennis against Roger.”