Jared Donaldson has been fined €5,000 following his angry exchange with umpire Arnaud Gabas at the Monte Carlo Masters on Monday.
During the second set of his first-round 6-3 6-3 loss to Albert Ramos-Vinolas, Donaldson squared up to Gabas when he insisted a serve from his opponent had landed out.
The official adjudged Ramos-Vinolas' ace to have clipped the line, but a furious Donaldson pointed at Gabas and shouted "show me the mark" before claiming "you're making up a mark because you don't like me."
Donaldson called for a supervisor and when Gabas said he had been aggressive, the world number 51 replied sarcastically: "Oh I'm sorry, I hurt your feelings. I apologise."
The 21-year-old was given a code violation at the time and on Tuesday the ATP confirmed he had been fined for unsportsmanlike conduct.