Roger Federer has added yet another record to his vast collection when he guaranteed becoming the oldest men's world number one by beating Dutchman Robin Haase 4-6 6-1 6-1 to reach the semi-finals of the Rotterdam Open.
Fresh from winning his 20th grand slam title in Melbourne this month, Federer took a wildcard into the ABN AMRO World Tennis event with his eyes fixed on a return to number one for the first time since November 2012 at the age of 36 years and 195 days.
Needing to reach the last four to overtake great rival Rafael Nadal, Federer showed some early nerves in his quarter-final clash in the port city's Ahoy Arena, dropping serve in the ninth game on his way to conceding the first set.
But the Swiss, as he usually does, moved through the gears to punish a physically struggling Haase.
A demoralised Haase double-faulted on match point and after an initially restrained celebration Federer sat on his chair and looked close to tears as his feat sank in.
Federer, whose glittering career has re-ignited since taking six months off in 2016, has won three of the last five grand slams having gone five years without one.
He surpasses Andre Agassi who was the previous oldest man to top the rankings. The US player was 33 when he scaled the summit in 2003.
Federer also set another record with the more than five-year gap between his previous and most recent stints as world number one being the longest since ATP rankings began in 1973.
Incredibly Federer first reached number one in 2004, as a 22 year old, and having now returned there 14 years later playing some of the best tennis of his career, he looks capable of another lengthy stretch on the throne.
He already holds the record of 302 weeks ranked number one.
Federer will face either Italian Andrea Seppi or young Russian Daniil Medvedev in the semi-final as he closes in on a 97th career title.