Roger Federer rarely loses his cool on the tennis court but having been broken in the third set and trailing Tennys Sandgren the Swiss maestro was handed an audible obscenity warning.
The 20-time Grand Slam champ was struggling against the American after easily taking the first set and was looking at going 3-0 down in the third set.
‘HE’S MARRIED’: Nick Kyrgios' hilarious quip for screaming Rafa Nadal fan
‘THIS IS A JOKE’: Australian Open match stopped for 10 minutes in 'wild' argument
But things took a turn when Federer mumbled something and the line judge approached the chair umpire and signalled he had made an audible obscenity.
This did not sit well with the normally cool mannered Federer.
He approached the line judge and was clearly asking what she thought he had said.
Federer then approached the chair umpire and minced words before playing out the game.
During the changeover Federer could be heard saying to the chair umpire: “If it was clear why didn’t you call it?”
“She is 100 per cent sure?”
He then went on to question the line judge.
“She is from Switzerland right?” Federer mockingly asked.
“Give me a break.”
Federer went on to produce an incredible comeback, saving seven match points to prevail in five sets.