The world No.7 defeated South Korea's Kwon Soon-woo 6-7(5), 6-3, 6-2, 6-4, but started slowly and was clearly frustrated when he smacked the ball with his racquet at the change of ends after losing the first set.
The ball rebounded off the court and narrowly missing the official's face as he swept the clay surface. It was so close in fact that it knocked off his hat.
Nobody noticed what had happened except the crowd, with Rublev continuing his dummy-spit by smashing a water bottle on the floor.
"I lost my mind for a moment, and of course I regret what I did. It's unacceptable to hit the way the ball I hit it," Rublev said.
"Better if I just hit the racquet on the seat, because the ball can affect someone.
"This is unprofessional from my side, and hopefully I will never do it again."
Fans online questioned why Rublev wasn't hit with a greater sanction other than a code violation, with the rules advocating for disqualification if such an incident occurs.
Serbian star Novak Djokovic was famously disqualified from the 2020 US Open after hitting a line judge with a ball that was not in play.
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