Rome - Second seed Novak Djokovic said he is on track to raise his game for the French Open after reaching the Rome Masters quarter-finals Thursday with a 6-4, 6-4 win over Spain's Roberto Bautista Agut.
Djokovic, beaten in the final by Britain's Andy Murray last year, will now face Juan Martin del Potro in the quarters after the unseeded Argentinian's 7-6 (7/4), 6-3 win over Japanese seventh seed Kei Nishikori.
Rafael Nadal, enjoying his best season on clay in two years, booked a quarter-final clash against Austria's Dominic Thiem, whom he beat in the Madrid Masters final last week, after an "aggressive" 6-3, 6-4 win over American Jack Sock, seeded 13th.
The Spaniard, a seven-time champion in Rome and now on a 17-match claycourt winning streak, also swept Djokovic aside in the semis in Madrid.
But French Open champion Djokovic said: "I'm getting closer, I feel like today's match was one of the better ones I've played on clay this season, and in the past couple of months.
"It's coming at the right time, we're getting closer to Roland Garros. All the players are looking to raise their game for Paris.
"I've been doing my best to optimise my game to get it to the highest possible level at the moment ... right now, as days are passing by, I feel more comfortable on the court, more confident hitting the ball."
It kept Djokovic on track to meet Nadal in the semis after the Spaniard ended Sock's hopes in 1hr 20min.
"It was a good victory against Jack, he's a tough opponent. He hit the ball hard with a lot of spin," said Nadal.
"I played a more aggressive game and I'm serving better. I can play a bit more aggressive than the way I played tonight, but overall I'm happy.
"Tomorrow I'm up against Dominic, he's a player who's having more success on clay so it will be another tough battle."
Thiem saved three match points in beating Sam Querrey 3-6, 6-3, 7-6 (9/7).
Another playing looking to up his game for the French Open is 2015 champion Stan Wawrinka but the world number three said a lack of confidence was to blame for his shock 7-6 (7/1), 6-4 defeat to big-serving American John Isner, who is ranked 24th in the world.
"When you lack confidence and rhythm, against opponents like (Benoit) Paire and Isner, it's not ideal," said Wawrinka, who had beaten Frenchman Paire 6-3, 6-4 on Wednesday.
"I had some chances to break him at the start of the match, but I didn't push him hard enough.
"My game and my physical condition are there. But confidence, you can lose it quickly. But I'll keep fighting."
Isner will now meet Marin Cilic after the sixth seed from Croatia beat Belgian David Goffin, the ninth seed, 6-3, 6-4.
Results on the fifth day of the Rome Masters on Thursday (x denotes seeding):
Rafael Nadal (ESP x4) bt Jack Sock (USA x13) 6-3, 6-4
Dominic Thiem (AUT x8) bt Sam Querrey (USA) 3-6, 6-3, 7-6 (9/7)
Juan Martin del Potro (ARG) bt Kei Nishikori (JPN x7) 7-6 (7/4), 6-3
Novak Djokovic (SRB x2) bt Roberto Bautista Agut (ESP) 6-4, 6-4
Marin Cilic (CRO x6) bt David Goffin (BEL x9) 6-3, 6-4
Milos Raonic (CAN x5) bt Tomas Berdych (CZE x12) 6-3, 6-2
John Isner (USA) bt Stan Wawrinka (SUI x3) 7-6 (7/1), 6-4
Alexander Zverev (GER x16) bt Fabio Fognini (ITA) 6-3, 6-3
Venus Williams (USA x9) bt Johanna Konta (GBR x5) 6-1, 3-6, 6-1
Simona Halep (ROM x6) bt Anastasia Pavlyuchenkova (RUS x12) 6-1, 4-6, 6-0
Anett Kontaveit (EST) bt Mirjana Lucic-Baroni (CRO x16) 6-1, 6-1
Garbine Muguruza (ESP x3) bt Julia Georges (GER) 7-5, 6-4
Daria Gavrilova (AUS) bt Svetlana Kuznetsova (RUS x7) 6-2, 5-7, 6-4
Kiki Bertens (NED x15) bt Ekaterina Makarova (RUS) 7-6 (7/3), 6-1
Elina Svitolina (UKR x8) bt Mona Barthel (GER) 3-6, 6-0, 6-0
Karolna Pliskova (CZE x2) bt Timea Bacsinszky (SUI) 6-1, 7-5