Rafael Nadal's surprise quarter-final exit at the Madrid Masters has seen the Spaniard replaced as world number one by Roger Federer in the latest ATP rankings published on Monday.
Federer returns to the top spot despite not having played since March. Former world No 1 Novak Djokovic slipped six places to 18th after his second round defeat in Madrid, his lowest ranking since October 2006.
Madrid winner Alexander Zverev remains in third, but the man he beat in Sunday's final, Dominic Thiem, dropped a place to eighth despite knocking out Nadal on his way to facing Zverev.
Thiem saw off Kevin Anderson in the semi-finals and it is the South African who inherits his seventh spot, the 31-year-old's highest ever ranking.
The highest mover in the men's charts is Madrid semi-finalist Denis Shapovalov with the Russian teenager jumping 14 rungs to a best ever 29th.
WTA: Kvitova up two places
Czech Petra Kvitova jumped two spots to eighth in the latest WTA rankings released Monday after beating Kiki Bertens to win the Madrid Open for the third time on the weekend.
Kvitova, who was also the champion in Madrid in 2011 and 2015, has now claimed four titles in 2018 after triumphs in St Petersburg, Doha and Prague.
losing Madrid finalist Bertens shot up five places to 15th, while Russian Maria Sharapova's quarter-final showing meant she went up 12 spots to 40th in the rankings headed by Romania's Simona Halep, Dane Caroline Wozniacki and Spaniard Garbine Muguruza.
Yuki at 94
Out of action Yuki Bhambri dropped eight places to 94 while Sasi Kumar Mukund, who made his first ever singles quarterfinals at Challenger level, jumped 45 places to career-best 377 in the ATP singles chart.
Yuki has not played since winning the Sanitaizi Challenger title in Taiwan due to a minor foot problem.
He resumed training last week and will be back in action at the Busan Open.
He will open his campaign against Yoshihito Nishioka in Busan on Tuesday.
Yuki had returned to top-100 after winning the Taiwan Challenger and has earned a direct entry into the French Open.
After Yuki, Ramkumar Ramanathan is the next best Indian in the singles chart at number 124 and is followed by Prajnesh Gunneswaran (175), Sumit Nagal (226, -2) and Arjun Kadhe, who gained 29 places to be at number 371.
Mukund, who reached the quarterfinals at Karshi Challenger after qualifying for the main draw, earned 22 ranking points to touch 377.