Rafa Nadal, Roger Federer and Novak Djokovic demonstrated their superior class on clay as they eased into the quarter-finals of the Monte Carlo Masters on Thursday.

Claycourt wizard Nadal barely broke a sweat in his 6-1 6-3 thrashing of Italy's Andreas Seppi while fourth seed Federer recovered from a break in the first set to beat Czech Lukas Rosol 6-4 6-1.

Champion Djokovic dropped just one game as he demolished Spain's Pablo Carreno Busta 6-0 6-1 to continue his title defence in the principality.

Spaniard Nadal, whose eight-year reign as champion was ended by Djokovic in the final last year, extended his proud record in Monte Carlo to 50-2 with the win on centre court.

The world number one will next meet compatriot and sixth seed David Ferrer in the final eight, who made easy work of Bulgaria's Grigor Dimitrov by winning 6-4 6-2.

"That is going to be a very tough match," the eight-times French Open champion told a news conference about the all-Spanish duel with Ferrer.

"David is a tough, tough player on any surface but here on clay, (he is) always a big challenge. I play a lot of matches against him, very tough ones."

Federer, who has a record 17 grand slam titles, will face local favourite Jo-Wilfried Tsonga in a mouth-watering quarter-final after the French ninth seed shook off a mediocre start to celebrate his 29th birthday with a 5-7 6-3 6-0 victory over Italy's Fabio Fognini.

"I think Jo played the semis here last year, so he's played here well in the past," Federer told a news conference.

"I've seen Jo play different kinds of quality matches lately so I'm not quite sure how he's going to play, how aggressive, how passive.

"I have to make sure I play aggressive myself and not become too passive just because we're on clay."

Djokovic, seeded second, will face either fifth seed Czech Thomas Berdych or Spain's Guillermo Garcia-Lopez, and he can look forward to a titanic semi-final showdown with Federer should they both get past their next opponents.

Swiss third seed Stanislas Wawrinka reached the quarter-finals without hitting a ball on Thursday after his third-round opponent Nicolas Almagro withdrew injured.

"I woke up this morning with a severe pain in my left foot that prevented me from even walking normally," Almagro said.

"After consulting with the doctor for a long time this morning, we decided together that it was better for me not to play today."

Australian Open champion Wawrinka advances to meet eighth seed Milos Raonic after the Canadian beat 11th-seeded Spaniard Tommy Robredo 6-4 6-3.