Tsitsipas, an Australian Open semi-finalist who also crashed out in the first round at Wimbledon, cramped in losing 6-4, 6-7 (5/7), 7-6 (9/7), 7-5 after three hours and 54 minutes.
The 21-year-old Greek star, who reached a career-best fifth in the world rankings earlier this month, suffered his fourth consecutive loss this month and said after he felt wronged by the Frenchman officiating the match.
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"This chair umpire, he has something against me. I don't know why," said Tsitsipas. "I feel like some of them have preferences when they are on the court."
It wasn't clear exactly what Tsitsipas meant when he yelled at Dumusois, "You're all weirdos," but he clearly wasn't happy about the idea his vocal father might be coaching him from the stands rather than simply cheering him.
"The chair umpire was very incorrect in what he was telling me during the match," Tsitsipas said. "I don't know what this chair umpire has in specific against my team but he's been complaining and telling me that my team talks all of the time when I'm out on the court playing.
"I believe he's not right, because I never hear anything of what my team says from the outside.
"My father outside, who usually does the talking, he's trying to pump me up by saying, 'Come on,' raising my confidence but not coaching, trying to boost me up."
Tsitsipas stopped short of calling it a factor in his loss but said he felt the impact.
"It's not very pleasant when you have the umpire give you warnings and time violations and coaching violations during a match," Tsitsipas said. "It can affect your thinking. It can affect your decision-making. And I sometimes believe there is nothing to give there."
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Tsitsipas admitted his loss to Stan Wawrinka in the French Open fourth round, a five-set thriller that took more than five hours, still stings.
"It was difficult," he said. "It's in the back of my head somewhere. I still feel it. I still feel the pain of that loss. I'm trying to erase it from my memory and move on.
"I want to be tough mentally and I want to constantly improve, become better. I cannot let things like that get into the way."
Tsitsipas also regretted how painful his first-round Wimbledon loss to Italy's Thomas Fabbiano felt at the time.
"I'm not going to react again like in Wimbledon," he said. "I saw myself in that interview a couple of days later and it didn't feel right. My reaction was too much.
"There are far worse things in life than losses, and that day felt like someone was in the grave. I don't know why I got upset so much about that loss."
Tsitsipas admitted the grind of the season has worn on him mentally.
"I feel like I'm doing the same thing over and over again and my brain can't really take it anymore," he said.
"I feel like I'm doing the same routines on the court, the same execution, the same strategies and everything.
And I feel like my mind is just -- I don't feel inspired. I play out on the court, and I don't feel like I'm chasing something."
What does inspire him is the memory of reaching fifth in the world.
"I was really excited when I saw that number five and my name next to it," Tsitsipas said.
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"Then I realized that to stay up there, I have to be very, very consistent during semifinals, finals, winning titles, and I don't know why that got in my brain a little bit.
"First-round, second-round losses are unacceptable anymore."
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