Novak Djokovic was left furious with himself in an angry Madrid Open practice session with coach Andy Murray before his opening match.
The Serbian tennis legend locks horns with Italian world No.44 Matteo Arnaldi in the second round on Saturday at the Spanish clay-court event.
Djokovic, 37, is currently gearing up for the second Grand Slam of the year with the French Open tournament getting underway on May 25 in Paris.
The 24-time major champion has endured some difficult results in recent weeks, suffering a shock early exit to Alejandro Tabilo in Monte Carlo.
It followed his defeat in the Miami Open final to Jakub Mensik and Djokovic’s emotions have now spilled over in a Madrid training session.
Novak Djokovic lashes out during Madrid Open practice session
During practice, with British coach Murray by his side, Djokovic lost his head after hitting a series of poor shots and unleashed an X-rated rant.
‘F*** this sport,’ Djokovic said, with the footage captured on camera and going viral on social media. ‘F*** tennis, f*** everything.’
Novak Djokovic retirement rumours continue to grow
There have been rumours swirling online that Djokovic may soon decide to retire from tennis with fellow Big Four stars Murray, Rafael Nadal and Roger Federer having already hung up their respective rackets.
Following his surprising defeat to Tabilo at the Monte-Carlo Masters, Djokovic was unusually downbeat and emotional in his post-match press conference, setting alarm bells ringing for his large army of fans.
‘It was actually more like the worst day,’ Djokovic said. ‘Look, I was hoping it was not going to happen, but it was quite a high probability I’m going to play this way.
‘I don’t know. Just horrible. Horrible feeling to play this way, and just sorry for all the people that have to witness this.’
It has long been thought that Djokovic will not retire until he gets his hands on a historic 25th Grand Slam singles trophy.
Should he manage it, it would move him clear of Margaret Court in the all-time record books for the player with the most major singles titles.
But there are genuine question marks over whether the fire is still there for Djokovic and if he still has what it takes to beat the very best players.
When he finally decides to end his career, Djokovic will surely go down as the greatest tennis player of all time.
He has already won two more Grand Slam titles than Nadal and four more than Federer, with Djokovic breaking many other records across his incredible career.
Speaking after his Miami Open final defeat to Mensik last month, Djokovic said: ‘When you start to play less good, start to lose early in the tournament, that’s when more questions appear.
‘More, I guess, inner voices which are bringing doubts and conversations of whether you should keep going and how much and so forth.’