Novak Djokovic kept his emotions in check following the death of his grandfather to reach the Monte Carlo Masters semi-finals on Friday, beating Dutchman Robin Haase 6-4 6-2.
The Serb was joined in the last four by seven-time champion Rafael Nadal who eased past Stanislas Wawrinka of Switzerland 7-5 6-4, winning his 40th consecutive match in the principality, a run dating back to 2005.
"It's been a tough week," said Djokovic, after receiving news on Thursday of the death of his grandfather Vladimir in Serbia.
"I'm just happy that I can play tennis. I'm sure he is supporting me from heaven. I remember him well. But this is life, you have to accept it. His spirit will always be with me."
Djokovic will face Tomas Berdych in the semi-finals after the Czech knocked out British third seed Andy Murray 6-7 (4-7) 6-2 6-3.
Nadal took his record over Wawrinka to a perfect 8-0 and will next face Gilles Simon who beat fellow Frenchman and fourth seed Jo-Wilfried Tsonga 7-5 6-4.
"Stan was playing well after beating (fellow Spaniard Nicolas) Almagro (in the third round)," said Nadal.
"I have a lot of respect for his game.
"I did well to beat him, he's a great player who is always difficult."
Djokovic's concentration wandered during his win in 77 minutes, losing serve in the first game but winning the next four.
He broke Haase to win the opener and took a 4-0 lead in the second only to find himself drifting as he lost the next two service games.
But the top seed prevailed on a second match point with a break of his Dutch opponent as Haase drove a leaping backhand into the net.
"I'm happy I stayed strong and was able to play my best tennis," said Djokovic.
"Under the circumstances, I played well. My emotions were up and down, and you could see that on the court."
Murray could only be frustrated with himself after a performance in which Berdych managed 16 break point chances and converted on five.
Murray had one opportunity on the Czech's serve but was unable to take advantage.
"There are a lot of things I would have liked to have done better, it takes a lot of time for me to do it (well) on this surface," said Murray, who was bidding to reach a third semi-final in four years.
"It doesn't come straightaway. Today is a good match to learn from because I was playing a top player who played very, very well."
Berdych girded for a battle on the clay under sunny skies after losing the 74-minute opening set in a tiebreaker.
The former Wimbledon finalist took his chances and profited from a Murray miscue in a struggle lasting for just over two and three-quarter hours.
"I had to stay in the fight after the first set," said the Czech.
"I had some bad luck in the tiebreaker, but my game started getting stronger.
"I hope to keep playing my best tennis on clay."