Roger Federer's incredible renaissance in the latter stage of his career took another upturn over the weekend as the Swiss legend returned the world number one spot.
Rafael Nadal, who has also enjoyed some scintillating form in the last 12 months, had previously held top spot having won two out of the year's four majors.
But victory against Robin Haase in the quarter-finals of the Rotterdam Open on Friday night saw Federer become the oldest number one ever at 36 years and 195 days to be precise.
Serena Williams had previously held that title, with the American being 35 when she lost world number one status in May of last year.
On the men's side of the game, eight-time Grand Slam winner Andre Agassi previously held the ranking record - he was 33 when he lost the number one spot in September 2003.
However, these statistics are only based on the current ATP World Rankings which began in 1973, when the ATP was founded.
In nearly 100 years of professional tennis prior to the rankings starting, there were bound to be world number ones who were older than Roger Federer.
Before 1973, all of the most prominent Tennis magazines worldwide, British The Daily Telegraph, American World Tennis, French L’Equipe amongst others, released their rankings at the end of the year.
Though it was not a structured, points-based system like the current one used by the ATP, and it was not official, there was still a unanimity about the verdict.
As a result, were there other players who could have been considered as the world number one at an older age than Federer?
Actually, there were two.
As per Tennis World USA, American Big Bill Tilden dominated Tennis in the early 1920s, winning the only two Wimbledon tournaments he competed in, in 1920 and 1921, and he also won 6 consecutive US Open titles from 1920 to 1925. He reached number one in the rankings at the age of 37.
The other player older than Federer was Australian Ken Rosewall, who was ranked number one just before turning 37.
So whilst Federer's glittering career should be cherished for as long as he is playing, he may have to stick around for another year or so at the top of the tree in order to be considered the undisputed oldest number one of all-time.
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