Top seed Novak Djokovic passed another test on his suspect right ankle when he posted a 4-6, 6-2, 6-2 win over Juan Monaco to join eight-time champion Rafael Nadal in the quarter-finals of the Monte Carlo Masters.
Djokovic will next take on Finn Jarkko Nieminen who spent 2 hours in knocking out Juan Martin del Potro 6-4, 4-6, 7-6 (7-4) to reach only his third clay quarter-final since 2006.
Third seed Nadal turned in a routine performance to dispatch German Philipp Kohlschreiber 6-2, 6-4 as the Spanish king of clay bids for a record ninth straight trophy at the event.
"I'm very excited to play in every tournament, and especially when I'm playing in a tournament like Monte Carlo," said Nadal, who won his 44th match in a row at the venue where he suffered his only loss a decade ago.
"To be excited is impossible, I feel more relaxed also."
Nadal will next line up against Grigor Dimitrov, who beat Germany's Florian Mayer 6-2, 6-2.
Second seeded Andy Murray, who has yet to win a claycourt title, collapsed to a 6-1, 6-2 loss to Stanislas Wawrinka.
The win for the Swiss in less than an hour guaranteed that Roger Federer returns to the No 2 ranking on Monday, sending Murray back to third.
The shell-shocked Scot committed 24 unforced errors. US Open champion Murray, a 2012 quarter-finalist, went nil for two on break points and lost his own serve five times in the rout.
"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 No 2 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 ..."
Djokovic played the role of ironman for a second day in succession as he overcame the ankle problem which had threatened to keep him from the event.
The Serb laboured through a second comeback in 24 hours to beat Monaco in just over two hours, with 25 winners and 45 unforced errors.
"I didn't know what to expect on court as I didn't feel so fresh this morning", said Djokovic.
"This was a great struggle and I'm glad to win it."