French player Hugo Gaston was fined 144,000 euros (£125,000) for his fourth example of unsportsmanlike conduct of the year - more than his 2023 earnings.
He dropped a spare ball from his pocket on to the court when opponent Borna Coric was about to smash a winner on set point at the Madrid Open in April.
If a second ball is deemed to have interfered with play, the umpire calls a let and the point is replayed.
Gaston, 22, appealed against the fine, which will be halved with conditions.
The governing body of men's tennis, the ATP, said the size of the fine reflected the fact the Frenchman - who ended up losing the match in straight sets to Coric - had been previously warned about similar incidents.
"Per ATP Rules in effect from 2023, fines related to unsportsmanlike conduct increase by 100% with each consecutive violation in the same season," the ATP said in a statement. "This was Gaston's fourth violation for unsportsmanlike conduct in the 2023 season."
It added the fine would be reduced to 72,000 euros (£62,000) "subject to certain conditions, including no further such violations incurred by Gaston over a 12-month probationary period".
World number 108 Gaston, who has been awarded a wildcard for the French Open, which starts on Sunday, has won about £98,000 in prize money this year.
Phone: (800) 737. 6040
Fax: (800) 825 5558
Website: 
Email: 
