WATCH | American tennis star in astonishing F-bomb tirade at umpire

There were ugly scenes at the Shanghai Masters tennis event on Wednesday when American tennis player Frances Tiafoe lost his cool and swore repeatedly at the umpire after losing his match to Russian to Russia's Roman Safiullin.

READ | Gruelling tennis schedule highlighted as Alcaraz runs from stadium to airport

Tiafoe, the world No 17, reacted angrily towards chair umpire Jimmy Pinoargote after losing 7-5, 5-7, 6-7 (5/7) to Russia's Roman Safiullin.

Tiafoe was upset after he was given a time violation serving 5-5 in the final set tie-break.

The American claimed he tossed the ball up to serve, but the umpire disagreed with his claims that it was a legitimate throw intended to start the point.

Pinoargote ordered Tiafoe to start the point with a second serve which aggravated the American. Safiullin then won the next two points to secure the match.

As Tiafoe walked towards the umpire's chair, he launched a flurry of expletives at Pinoargote in a prolonged outburst.

the drama at the end of the tiafoe/safiullin match pic.twitter.com/HftfltXHew

According to ATP Tour rules, Tiafoe could face a fine of up to $60 000 as a verbal abuse offence.

A post shared by Tennis TV (@tennistv)

Tiafoe later took to social media to show remorse for his actions.

"I really apologise for the way I acted tonight," he wrote on Instagram.

"That is not who I am and not how I want to treat people. I let my frustration in the heat of the moment get the best of me and I'm extremely disappointed with how I handled the situation.

"That's not acceptable behaviour and I want to apologise to the umpire, the tournament and the fans."