MONTE CARLO - World number one Novak Djokovic raised his eyes and arms to the sky after beating Ukraine's Alexandr Dolgopolov to reach the Monte Carlo Masters quarter-finals on Thursday just hours after learning of the death of his grandfather.

The Serb, who was told about his loss while practising in the morning, struggled to control his emotions when he walked on court for the match and then broke down in tears after completing a gutsy 2-6 6-1 6-4 win over Dolgopolov.

Novak Djokovic of Serbia clasps his hands and looks skywards after defeating Alexandr Dolgopolov of Ukraine during the Monte Carlo Masters in Monaco April 19, 2012.[Photo/Agencies]

Rafa Nadal ominously moved a step closer to winning a record eighth consecutive title at the principality by demolishing  Kazakhstan's Mikhail Kukushkin 6-1 6-1.

Nadal will face Swiss Stanislas Wawrinka, who defeated Spanish eighth seed Nicolas Almagro 6-3 6-3.

Rafael Nadal of Spain returns the ball to Mikhail Kukushkin of Kazakhstan during the Monte Carlo Masters in Monaco April 19, 2012.[Photo/Agencies]

In a humid and grey afternoon next to the Mediterranean, Djokovic was warmly welcomed by a packed crowd as the news of his loss spread in the Monte Carlo Country Club alleys.

He was crying as he left the court to thunderous applause two hours later.

"It was very hard for him to play. After he won, he just felt totally exhausted physically, mentally and emotionally," an ATP statement said.

As the unpredictable Ukrainian started to misfire in the second set, Djokovic regrouped and took advantage of the flurry of unforced errors flying off his opponent's racket.

The Serb, who earlier this month had described his grandfather as "my hero and a fighter... who is always sending me lots of positive energy", screamed out loud after he broke Dolgopolov's serve early in the second set.

Even a rain delay in the third set could not unsettle Djokovic and the Serb started weeping the moment he booked his place in the last eight.

Djokovic, who could become the first man in over 40 years to hold all four majors simultaneously if he triumphs at the French Open, will next face Dutchman Robin Haase.

Novak Djokovic of Serbia leaves the court crying after defeating Alexandr Dolgopolov of Ukraine during the Monte Carlo Masters in Monaco April 19, 2012.[Photo/Agencies]

Rain and fall

The morning sunshine proved to be a false dawn at the club which was soon drenched in rain. World number four Andy Murray, however, dodged the showers after France's Julien Benneteau retired hurt.

Murray was leading their fiercely contested opening set 6-5 when Benneteau quit, having fallen in the previous game when sliding to a wide ball. Benneteau received lengthy treatment before deciding that he could not continue.

The Frenchman said he had broken an elbow and sprained his ankle and would now miss the French Open which starts next month.

Murray was applauded as he brought ice bags to his opponent, who fell on the same spot of the court where Argentina's Juan Monaco badly sprained his ankle in his first round.

"The court, in parts, it's not flat, Murray told reporters.

"They said they had a few problems with it during the Davis Cup but they changed it. Clay courts usually take a while, if you make changes to them, before they've kind of settled.

"That's probably why there were a few bad bounces and guys are kind of struggling with the movement a little bit."

Murray will take on Czech Tomas Berdych, the sixth seed, who defeated Kei Nishikori 2-6 6-2 6-4.

Julien Benneteau of France grimaces in pain after being injured during his match against Andy Murray of Britain at the Monte Carlo Masters in Monaco April 19, 2012.[Photo/Agencies]

As the weather turned grey and cooled down, France's Jo-Wilfried Tsonga, the fourth seed, shrugged off two rain delays to beat Spaniard Fernando Verdasco 7-6 6-2.

He will meet compatriot Gilles Simon, the ninth seed, who moved past Serbia's Janko Tipsarevic 6-0 4-6 6-1.