Monte Carlo - World number one Rafael Nadal cruised to a 6-3, 6-2 victory over Russian Karen Khachanov on Thursday to set up a "difficult" Monte Carlo Masters quarter-final against Dominic Thiem, after the Austrian stunned Novak Djokovic.
Nadal needs to win an 11th Monte Carlo title to stay clear of Roger Federer at the top of the world rankings, and the 16-time Grand Slam champion made short work of Khachanov.
Khachanov held his own at times in the opening set, but Nadal moved through the gears and claimed his second comfortable victory of the week after his opening win over Aljaz Bedene.
"A good victory. Straight sets against a difficult opponent. That's the real thing," said Nadal.
Thiem should provide a sterner test in the last eight, after the fifth seed came from a set down to beat Djokovic.
Nadal has lost twice to Thiem on clay, but produced a dominant display in the French Open semi-finals last year en route to his 10th Roland Garros title.
"It's going to be a difficult match," the 31-year-old Nadal added.
"(He) is a player that plays so good in every surface, but especially on clay. He hits the ball hard.
"I can't let him play from good positions because he has lot of power... I need to play aggressive, with a higher intensity than him, then we'll see."
Nadal wasted no time in making his presence felt on Thursday, breaking to love in the second game as Khachanov felt the brunt of the Spaniard's forehand.
But the big-hitting Russian grew into the match and broke back as Nadal sent a backhand spinning wide.
That was as good as it got though for Khachanov, as Nadal quickly restored his two-game cushion and served out the opening set to love.
Nadal is bidding for a record 31st Masters title and 24th on clay, and he was far too good for his 21-year-old opponent in the second set.
Thiem, a two-time French Open semi-finalist, was the better player for much of his match against Djokovic and won 6-7 (2/7), 6-2, 6-3.
The Austrian says he will take confidence from his previous wins against Nadal into Friday's clash.
"It's (a) way better feeling if you go against him and know that you've beaten him already on this surface," said the 24-year-old Thiem.
"But it's the ultimate challenge for everybody, to play against him. I have to raise my level again. I think I'm able to do that."
Former world number one Djokovic has still not reached a quarter-final since Wimbledon last July after struggling with a right elbow injury.
The 12-time Grand Slam champion, now ranked 13, had said he was pain-free in Monte Carlo for the first time in two years, but Thiem backed up his French Open quarter-final win over the Serbian from last year with another impressive victory.
Earlier on Thursday, third seed Alexander Zverev came through a three-set tussle with fellow German Jan-Lennard Struff 6-4, 4-6, 6-4.
But Frenchman Richard Gasquet denied Zverev a meeting with his older brother Mischa by seeing off the serve-and-volleyer 6-2, 7-5 to claim his 500th win on the ATP Tour.
Belgian sixth seed David Goffin held off a late fightback from Roberto Bautista Agut to reach the last eight with a 6-4, 7-5 win, in a match that saw the Spaniard accidentally hit a ball boy with the ball.
Bautista Agut was given a code violation and later fined 2,500 euros ($3,085) for unsportsmanlike conduct.
Goffin will play fourth seed Grigor Dimitrov for a place in the semi-finals in a repeat of last year's ATP Tour Finals final, after the Bulgarian came back from a set and a break down to beat Germany's Philipp Kohlschreiber 4-6, 6-3, 6-4.
Second seed Marin Cilic is also into the last eight, after Milos Raonic pulled out with a right knee injury before their third-round match on Thursday.
Croatia's Cilic will take on Kei Nishikori in the quarter-finals, after the Japanese continued his return to form by beating Italian qualifier Andreas Seppi 6-0, 2-6, 6-3.
Monte Carlo Masters results on Thursday (x denotes seeding):
Rafael Nadal (ESP x1) bt Karen Khachanov (RUS) 6-3, 6-2
Dominic Thiem (AUT x5) bt Novak Djokovic (SRB x9) 6-7 (2/7), 6-2, 6-3
Alexander Zverev (GER x3) bt Jan-Lennard Struff (GER) 6-4, 4-6, 6-4
David Goffin (BEL x6) bt Roberto Bautista Agut (ESP x11) 6-4, 7-5
Marin Cilic (CRO x2) bt Milos Raonic (CAN x14) - walkover
Grigor Dimitrov (BUL x4) bt Philipp Kohlschreiber (GER) 4-6, 6-3, 6-4
Richard Gasquet (FRA) bt Mischa Zverev (GER) 6-2, 7-5
Kei Nishikori (JPN) bt Andreas Seppi (ITA) 6-0, 2-6, 6-3