Frances Tiafoe has apologised after he yelled “f*** you” at the umpire and refused to shake his hand after a controversial defeat to Roman Safiullin at the Shanghai Masters.

The American lost 5-7 7-5 7-6 (5) in a third-round match that hinged on a heated third-set tiebreak and a contentious moment.

Tiafoe, who reached the US Open semi-finals last month, was given a time violation at 5-5 in the deciding tiebreak after tossing the ball.

The umpire ruled that Tiafoe had not intended to serve following his ball toss, so took away his first serve on the point.

Tiafoe appealed the umpire’s decision, remonstrating that he “tossed the ball” and was “ready to serve”, but the umpire said he was on his second serve.

Tiafoe then lost the point, giving Safiullin match point, which the Russian won to claim the tiebreak 7-5 and advance to the fourth round.

After shaking hands with Safiullin at the net, Tiafoe walked off court and shouted at the umpire “f*** you man,  f*** you, seriously.”

Tiafoe walked underneath the umpire’s chair without a handshake and continued swearing as he returned to his seat.

The 13th seed could expect to receive a punishment for his outburst at the umpire if the ATP decides his rant was a violation of their rules. The American later posted an apology on Instagram for the way he acted.

“That is not who I am and not how I ever 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,” he said.

“That’s not acceptable behavior and I want to apologize to the umpire, the tournament, and the fans.”

In 2022, Alexander Zverev was hit with a fine of $40,000 and ejected from the Mexican Open after attacking the umpire’s chair with his racquet and calling him a “f***ing idiot”.

The ATP said Zverev committed aggravated behaviour but the German received a suspended ban of eight weeks.

Elsewhere in Shanghai, Novak Djokovic beat Flavio Cobolli and the 24-time grand slam champion will play Safiullin in the fourth round.

Djokovic, playing his first ATP Tour event since the US Open, needed only 64 minutes to dispatch Italian Cobolli 6-1 6-2.

Wet weather has badly affected the schedule in Shanghai and Cobolli had come through a two-and-a-half-hour tussle with Stan Wawrinka on Monday.

Veteran Gael Monfils upset his French countryman Ugo Humbert 7-6 (7) 2-6 6-1.

Monfils, 38, will next face third seed Carlos Alcaraz, who he defeated in their last meeting in Cincinnati in August.

There were also wins for seventh seed Taylor Fritz, Stefanos Tsitsipas, Ben Shelton, Grigor Dimitrov and Holger Rune.

Includes reporting from PA