Roger Federer dropped just one set on course to the Rotterdam Open title and it was in the quarter-finals against Robin Haase.
The Spaniard will not directly target usurping Federer as he enters "important" period of the season starting at the Mexican Open.
The 36-year-old may have become the oldest world number one ever - but who outperformed him last week?
It will be hard for anyone to surpass Roger Federer and Rafael Nadal in 2018, according to the former's ex-coach.
Former world number one Novak Djokovic has been backed by his coach Andre Agassi to make a return to the top.
Federer won the Rotterdam Open after beating Cilic in the Australian Open, picking up his 97th title in his illustrious career.
Federer decided to play less, change his racquet, shorten his matches and play even more forward so as to not exert himself beyond his capacity.
Federer has made history by becoming the oldest world number one, eclipsing the record set by Andre Agassi way back in 2003.
Roger Federer has reflected on an unforgettable week for him that saw him become world number one again and win his 97th career title.
Federer delivered his best performance of the tournament to sweep past the man once called 'Baby Fed', who seemed to suffer an injury in the embryonic stages of the second set.
Federer leapfrogged Nadal in the world rankings after reaching the semi-finals of the Rotterdam Open.
Andre Agassi has revealed which players he feels are capable of challenging Roger Federer, Rafael Nadal, Novak Djokovic and Andy Murray.
Federer became the oldest world number one in tennis following his quarter-final victory over Robin Haase at the Rotterdam Open.
Former world number eight Peter Fleming has cast doubts as to whether Roger Federer is 100% fit ahead of his Rotterdam Open final with Grigor Dimitrov.
World number one Roger Federer previews his Rotterdam Open final against Grigor Dimitrov in what he calls an "interesting" match for him.