Roger Federer's path to becoming the ATP men's singles world number one became a touch easier after Stan Wawrinka succumbed in the first round of the Rotterdam Open on Tuesday (13 February).
The Swiss ace has to make it to at least the semi-finals of the event in the Netherlands to replace long-time rival Rafael Nadal at the top of the rankings and it was believed that compatriot Wawrinka, who was expected to face Federer in the quarter-finals, would be a potential obstacle between him and his record-breaking achievement.
The 36-year-old will become the oldest number one ranked player beating Andre Agassi's record if he makes it to the semi-final and following Wawrinka's defeat his progress to the last four looks increasingly likely.
The 32-year-old, who is coming back from a long-term knee injury that required surgery in 2016, went down in three sets to local wildcard entrant Tallon Griekspoor. Wawrinka won the first set 6-4 but lost the next two 3-6, 2-6 to end his week early.
Federer was hoping to face his compatriot in the last eight of the competition – comparing their potential showdown to a major final. Wawrinka's loss provides an opportunity to the Dutch youngster, who will next face the winners of Robin Haase and Thiemo de Bakker.
Federer, meanwhile, will play his first match of the tournament against Belgian qualifier Ruben Bemelmans on Wednesday (14 February) with the winner facing Germany's Philipp Kohlschreiber.
Federer will be keen to win the Rotterdam title for the third time in his career after revealing that the event is special as it is one of the first tournaments he played after turning pro in 1998, but Alexandre Zverev could be a potential roadblock if he makes it to the semi-finals after the third seed made it to the second round with a straight-sets win over David Ferrer.