A Miami Open star threatened to sue tennis' governing body and called its chairman a 'f---ing a--hole' during a foul-mouthed on-court rant

• Vasek Pospisil threatened to sue the ATP and called its chairman a "f---ing a--hole."
• The Canadian made the comments as he crashed out of the Miami Open in the first round on Wednesday.
• Last year, Pospisil and Novak Djokovic launched a new players' association to rival the ATP.

Canadian tennis star Vasek Pospisil threatened to sue the ATP and called its chairman a "f---ing a--hole" as he crashed out of the Miami Open in the first round on Wednesday.

The 30-year-old made the comments towards the chair umpire in the first set changeover during his 3-6, 6-4, 3-6 defeat to Mackenzie McDonald of the United States.

He had already broken two rackets, smashed a ball out of the court, and been handed a verbal abuse point penalty before the outburst.

"What's happening with you?" - umpire Arnaud Gabas asked Pospisil at the end of the first set.

Pospisil replied angrily, saying his frustration was caused by ATP Chairman Gaudenzi grilling him during a players' meeting on Tuesday.

"An hour and a half the chair of the ATP f---ing screaming at me in a player meeting for trying to unite the players," Pospisil said.

Last year, Pospisil and world No. 1 Novak Djokovic launched a new players' association to rival the ATP that it says aims to increase the power of the players.

The organization has faced backlash from the sport's governing bodies and other players, including Roger Federer and Rafael Nadal.

"For an an hour and a half. The leader of the ATP. F--king a--hole. Get him out here. Why am I supporting this?" added Pospisil.

"If you want to default me, I'll gladly sue this whole organization."

After the outburst, Pospisil went on to win the second set, but ultimately lost in third and final set and exited the tournament.

Shortly after the match, the Canadian tweeted to say he was sorry for his actions.

"I want to sincerely apologize for my behavior on the court in Miami earlier today," he said. "I disrespected the game I love and for that I am truly sorry.

"By way of explanation, I felt deeply unnerved during a meeting between players and ATP executives last night, and I underestimated the toll those emotions took on me until I stepped onto the court today. Again, I am sorry for my on-court behavior and the language I used."

After his victory, McDonald will now face fellow American John Isner in the second round of the tournament on Friday.