Roger Federer will return to second in the ATP standings next week after Andy Murray collapsed to a 6-1, 6-2 third-round loss to Stanislas Wawrinka at the Monte Carlo Masters on Thursday.
A shell-shocked Murray committed 24 unforced errors as he lost to Federer's Swiss compatriot, seeded 13th, in 58 minutes.
Murray, a quarter-finalist here a year ago, went nil for two on break points and lost his own serve five times in the rout which sends him back to the practise court for the next fortnight in hopes of repairing his game for the Madrid Masters in early May.
"I made a lot of mistakes, 24 unforced errors is far too many. That's a set's worth. That's where half the points went," said Murray who had regained the number two world ranking on the strength of his win in the miami Masters.
"I've played some good tournaments here. But, yeah, it does take me time to feel comfortable on the surface.
"I need matches against top players to see what's going wrong and what's going right, things I need to work on to get better.
"Normally towards the end of the clay court season, I start to feel better with my game and I've had some good results, but at the start I have struggled a little bit."
Rafael Nadal stepped up his campaign for an historic ninth straight title at the event as the third seed won his 44th match in a row at the venue with a 6-2, 6-4 defeat of German Philip Kohlschreiber.
The Spanish great lifted his record at the seaside Country Club to 46-1 at a tournament where he suffered his lone defeat in 2003 against Guillermo Coria.
Nadal will next line up in the quarter-finals on Friday against Grigor Dimitrov, who beat Germany's Florian Mayer with an identical 6-2, 6-4 scoreline.
Nadal advanced in 80 minutes and earned revenge for his only loss to Kohlschreiber from 10 meetings, a grass quarter-final defeat from last summer in Halle.
This win was his 16th in a row after successive titles this season in Indian Wells and Acapulco.
"It was a great win for me," said Nadal, who follows the same script for every victory. "I'm very happy.
"Every match is a new one for me, every day is completely different. We will see what goes on tomorrow. But I just love playing here and feel a great emotion every time I step onto the court here."
Unpredictable Italian Fabio Fognini sprung a surprise on fourth seed Tomas Berdych, dismissing the Czech 6-4, 6-2. French sixth seed Jo-Wilfried Tsonga thrilled his home fans as he overwhelmed Austrian Jurgen Melzer 6-3, 6-0.
"It's difficult to assess my game because he was not really playing his best," Tsonga said of the below-par Melzer. "But I'm happy I was able to do the job.
"When you play tennis, you always try for perfection. Of course, sometimes you can't reach that. I'm happy with my game today. Of course, there are always some things you can improve."
The world number one Serb was testing his injured right ankle for a second straight day as he played Argentine Juan Monaco.