Novak Djokovic accused Cameron Norrie of unsportsmanlike behaviour after a frosty encounter in the fourth round of the Italian Open.
The world number one ultimately eased to 6-3 6-4 victory but there was a flashpoint where Norrie hit Djokovic with a smash, and the handshake at the net lacked any warmth.
The main talking point came in the fourth game of the second set as Norrie sought to retrieve an early break.
Djokovic turned his back on the play after presenting his opponent with an easy overhead, only for Norrie, seemingly unintentionally, to drill the ball into the Serbian's legs, who responded with an extremely hard stare.
Speaking to reporters afterwards, Djokovic was less bothered by that incident than Norrie's overall demeanour coupled with a medical timeout he took prior to the final game.
"I did watch the replay when he hit me," said the six-time champion. "Maybe you could say he didn't hit me deliberately. I don't know if he saw me.
"I mean, (in your peripheral vision) you can always see where the player is positioned on the court. The ball was super slow and super close to the net. I just turned around because the point was over for me.
"It was not so much maybe about that, but it was a combination of things. 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 'C'mon' in the face more or less every single point.
"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.
"I got along with Cameron really well all these years that he's been on the tour. Practised with each other. He's a very nice guy off the court, so I don't understand this kind of attitude on the court, to be honest.
"But it is what it is. 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. That's all it is. What happens on the court, we leave it on the court, and we move on."
Norrie, who had lost both his previous meetings with Djokovic, dropped serve at the start of the contest and was kept at arm's length through the rest of the opening set, with the Serbian putting on a tactical masterclass.
Norrie withstood pressure after the smash incident to hold his serve until 4-4, when Djokovic, who has never failed to make the quarter-finals in Rome, made the decisive move.
The 35-year-old was serving noticeably slower than usual but he was coy on the reason for a visit to the treatment room that delayed the start of the match.
"Every day is something," he said. "Thankfully I was able to play and finish the match, so hopefully tomorrow I will feel even better."
Djokovic next faces a quarter-final clash with seventh seed Holger Rune, who defeated Alexei Popyrin in three sets, while fifth seed Stefanos Tsitsipas completed a delayed 6-3 7-6 (3) victory over Italian Lorenzo Sonego.
READ MORE: Novak Djokovic dodges Cameron Norrie in Rome to reach Italian Open quarter-finals