Roger Federer became the oldest number one singles player in tennis history by beating Robin Haase in the World Tennis Tournament quarter-finals in Rotterdam.
The 36-year-old Swiss, who won his 20th grand slam last month by claiming a sixth Australian Open title, replaced Rafael Nadal at the top of the ATP rankings with a 4-6 6-1 6-1 victory over Dutchman Haase.
Federer has surpassed Andre Agassi as the oldest player to occupy the summit of the men’s game - the American was 33 when he was last on top in September 2003.
His return to the top spot will be formally rubber-stamped when the men’s tour rankings are published on Monday morning.
Federer also beats the mark set by the record holder in the women’s game, Agassi’s American compatriot Serena Williams, who was 35 when she was last number one in May last year.