ROME (AP) — Novak Djokovic's angry glare made it clear how furious the 22-time Grand Slam champion was with his opponent.

And it wasn’t just because Cameron Norrie hit him in the left calf with an overhead smash after Djokovic had already turned his back and conceded a point early in the second set of the Serb's 6-3, 6-4 win on Tuesday.

There were also other instances of bad sportsmanship from Norrie, Djokovic said after reaching the Italian Open quarterfinals for the 17th straight year.

Djokovic also took issue with how his British opponent took a medical time out just before he served out the match.

“I did watch the replay when he hit me. Maybe you could say he didn’t hit me deliberately," Djokovic said when asked about his angry glare toward Norrie after the incident. "It was not so much maybe about that. ... From the very beginning, he was doing all the things that were allowed. He’s allowed to take a medical timeout. He’s allowed to hit a player. He’s allowed to say ‘Come on’ in the face more or less every single point from basically first game.

“Those are the things that we players know in the locker room it’s not fair play, it’s not how we treat each other," Djokovic said. “He brought the fire, and I responded to that. I’m not going to allow someone behaving like this just bending my head. I’m going to respond to that.”

Clearly motivated by Norrie's behavior, Djokovic produced his best clay-court performance of the year against the 13th-seeded Norrie, who was not made available for comment.

Aiming for his seventh title on the red clay of the Foro Italico, Djokovic had his entire game clicking after struggling at times in the previous rounds and in his previous two tournaments on clay.

On an overcast day after it had rained all morning, Djokovic appeared focused from the start.

“I actually finished my warmup 10 minutes before I went on the court. So I was rushing a bit with everything but we couldn’t (warm up) earlier because of the rain," Djokovic said. "So I’m just glad to overcome today’s challenge in straight sets and move on.”

Djokovic was seen in the trainer’s room before the match, having taken three weeks off before this tournament because of a lingering issue with his surgically repaired right elbow.

“Every day is something,” the 35-year-old Djokovic said, without specifying what was bothering him. “But thankfully I was able to play and finish the match, so hopefully tomorrow it will feel a bit better.”

Djokovic committed less than half as many unforced errors as Norrie, 14-29; and had two more winners, 21-19.

Norrie won a title on clay in Rio de Janeiro earlier this year, beating Carlos Alcaraz in the final.

Djokovic will lose the No. 1 ranking to Alcaraz after this tournament — even though Alcaraz was beaten by 135th-ranked Hungarian qualifier Fabian Marozsan in the third round on Monday.

Alcaraz will therefore be seeded No. 1 and Djokovic will be No. 2 at the French Open, which starts in 12 days.

Djokovic will next face seventh-seeded Holger Rune in a rematch of the Paris Masters final that the 20-year-old Dane won in November. Rune beat Australian qualifier Alexei Popyrin 6-4, 5-7, 6-4.

“He kind of reminds me a little bit, the way he plays,” Djokovic said of Rune. "Really fit physically, great defense, but also great counter-puncher. He can hurt you from both forehand and backhand side. Really solid serve. Aggressive returns. Just all-around player on all surfaces.

Rune reached the final of the Monte Carlo Masters last month.

“It’s going to be a very physical match,” Djokovic said.

Also, 2017 champion Alexander Zverev finished off a 6-4, 7-5 win over J.J. Wolf in a match that was suspended because of rain at 3-3 in the second set on Monday.

Zverev will play again later against Daniil Medvedev in a 15th career meeting between the pair.

Stefanos Tsitsipas eliminated Lorenzo Sonego 6-3, 7-6 (3) in another match that began on Monday. Tsitsipas will play later against another Italian, Lorenzo Musetti, in the night session.

Musetti rallied past Frances Tiafoe 5-7, 6-4, 6-3 in a match that was also suspended.

In women’s action later on Campo Centrale, two-time defending Rome champion Iga Swiatek was playing Donna Vekic.

___

Andrew Dampf is at https://twitter.com/AndrewDampf

___

AP Tennis: https://apnews.com/hub/tennis and https://twitter.com/AP_Sports