Frances Tiafoe screamed "f*** you" at the umpire as he lost a close three-setter at the Shanghai Masters.

The American appeared calm as he shook hands with Roman Safiullin after losing a three-hour thriller in a final set tiebreak.

But he erupted as he approached the chair official, screaming and swearing at him repeatedly and refusing to shake his hand.

Tiafoe and Safiullin found themselves embroiled in a tight contest in the third round of the Shanghai Masters on Tuesday. After going down a break in the decider, the world No. 17 kept himself alive and broke when Safiullin served for it.

They headed into a tiebreak, where Tiafoe was slapped with a time violation at 5-5. It wasn't his first in the match, meaning it came with a loss of first serve at a crucial moment.

"Time violation, loss of serve. Mr Tiafoe," umpire Jimmy Pinoargote announced. Tiafoe immediately stormed up to the chair.

"No. No, no, no. I tossed the ball up. I tossed the ball up. I tossed the ball. I was back behind and I tossed the ball. I tossed the ball and I was ready to serve," he protested.

But the chair official wasn't having it. "I’m not buying this. It’s a second serve now," he replied.

Tiafoe continued: "I tossed the ball I was ready to serve. Dude that’s the rule. The ball goes up, how am I not ready to serve?" The umpire continued to announce that it was a "second serve" as the American ranted.

The 13th seed eventually retreated to the baseline and hit a conservative second serve. Safiullin won the point in a thrilling exchange and got the job done with an ace, winning 5-7 7-5 7-6(5).

After the tiebreak drama, Tiafoe let his frustrations out as soon as the match was done. After shaking hands with the world No. 61, he turned his attention to the umpire. "F*** you man. F*** you. Seriously man. You f***ed me the f***ing match," Tiafoe shouted.

"Three f***ing hours and you’re going to do that. Why? You f***ed the match up. Great f***ing job. F***."

Sky Sports commentators only saw the match point and were left bewildered by Tiafoe's reaction, immediately apologising for his sweary outburst. "Well apologies for the language of Frances Tiafoe. Quite the outburst there at the end," Jonathan Overend said.

Colin Fleming added: "My goodness. He's completely lost the plot there, that is going to be a sizeable fine coming his way. You might feel aggrieved with something that’s happened but you can’t speak to anyone like that."

When they eventually watched a replay of the second serve incident, both commentators sided with the umpire. "He didn’t toss the ball up to serve, did he?" Overend remarked.

Fleming replied: "It wasn’t a legitimate throw-up though, was it? He tried to buy himself some time. [The umpire] has enforced the rules."