Monte Carlo: 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 two and a half 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, 6-4.
The win was the Spaniard's 17th in a row after successive titles this season in Sao Paulo, Acapulco and Indian Wells.
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 number two ranking on Monday, sending the 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 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."
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.
"It was another great fight, I'm trying to take it day by day," said Djokovic.
"I didn't know what to expect on court as I didn't feel so fresh this morning.
"But I managed to come back, it was a good win for me on clay against a good player. I tried to keep the points as short as possible and I served well when I needed to.
"I'm feeling better on my ankle. This was a great struggle and I'm glad to win it."
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.