Roger Federer will not only become the oldest man to reach world number one on Monday, but his latest ascent to the top will mark the longest gap between stints at the summit.
MORE: This one means the most - emotional Federer revels in return to the top
The seemingly ageless Federer will regain his status as the best male player on the planet on Monday after beating Robin Haase to reach the semi-finals of the Rotterdam Open.
At 36, Federer beats the previous record of Andre Agassi as the oldest man to top the ATP rankings, but a gap of what will be five years and 106 days since the last time he held top billing in November 2012 is also a new benchmark.
Previously, Agassi also held that record, having gone three years and 142 days between 1996 and 1999, while fellow greats Jimmy Connors and Rafael Nadal also feature in the top five.
Longest Gap Between Stints as @ATPWorldTour No. 1
— ATP Media Info (@ATPMediaInfo) February 16, 2018
1 @RogerFederer 5 years, 106 days*
2 @AndreAgassi 3 years, 142 days (1996-99)
3 @JimmyConnors 3 years, 65 days
4 @RafaelNadal 3 years, 45 days
5 Andre Agassi 2 years, 228 days (2000-03)
* As of Monday, 19 February 2018
Perhaps even more remarkably, the gap of 14 years and 17 days between Federer first becoming number one and his latest stint at the top is another landmark.
Federer's great rival Rafael Nadal previously held that distinction, having gone nine years and 184 days between first reaching the summit and last claiming the number one spot.
Longest Gap Between First and Most Recent Day as @ATPWorldTour No. 1:
— ATP Media Info (@ATPMediaInfo) February 16, 2018
1 @RogerFederer 14 years, 17 days*
2 @RafaelNadal 9 years, 184 days
3 @JimmyConnors 8 years, 339 days
4 @AndreAgassi 8 years, 150 days
5 Pete Sampras 7 years, 221 days
* As of Monday, 19 February 2018