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, meeting Wawrinka for the first time in six years, will now meet Marin Cilic after the sixth seed from Croatia beat Belgian David Goffin, the ninth seed, 6-3, 6-4.
In the women's tournament, Venus Williams overcame determined Briton Johanna Konta to win their third-round clash 6-1, 3-6, 6-1.
In the absence of sister and defending champion Serena, she will now meet Spain's Garbine Muguruza on Friday for a place in the semis and a possible match-up with Czech second seed Karolina Pliskova.
Williams, competing in Rome because "I still have a lot to give", was more circumspect about her chances of emulating Serena by winning Roland Garros.
"It's so different when you're talking about it or when you're playing it," she said.
"When you're playing it, it's a lot of work. There is not even one point that is given."
Russia's Svetlana Kuznetsova, the seventh seed, suffered a 2-6, 7-5, 6-4 defeat to Australian qualifier Daria Gavrilova.
Gavrilova will meet Dutch 15th seed Kiki Bertens after she beat unseeded Russian Ekaterina Makarova 7-6 (7/3), 6-1.
source: news.abs-cbn.com
