Australian coach Roger Rasheed is fed up with maligned countryman Bernard Tomic's on-court persona, urging the world number 22 to either "show some passion" or "leave the sport".
Rasheed was speaking just hours after Tomic acknowledged he had to improve his public image following his controversial comments at the Madrid Open.
Tomic said "would you care if you were 23 and worth $10million" in response to allegations of tanking on match point, when he held the head of his racquet instead of the handle against Fabio Fognini in Madrid.
The 23-year-old, who also retired eight minutes into his first-round match at the Internazionali d'Italia earlier this month, has since ruled himself out of the Olympic Games in Rio de Janeiro following the backlash and warnings from Australian Olympic team boss Kitty Chiller about his "appalling" behaviour.
And after watching Tomic advance to the second round of the French Open in straight sets on Tuesday, Rasheed - a former mentor of Lleyton Hewitt and Grigor Dimitrov - was less than impressed as he launched a scathing attack on the three-time ATP Tour winner.
"To be honest, I would beat [opponent] Brian Baker. He has had that many injuries, he's ranked 600-and-something in the world," Rasheed said Australian radio station 2KY.
"He couldn't hit two balls on the court. It's not about that, it's about what I turn up and look like.
"I don't care whether you like clay, I don't care whether it's played on ice or a bed of nails.
"When you turn up to a grand slam or any professional event, you have to show that when you step on the court that you have to have a persona that shows passion, that shows hunger and that shows commitment to a sport that you supposedly love."
Rasheed continued: "When you go on the court and even if you didn't like the surface, that's even more of a more reason to put on a persona that you're passionate about the competition because you've got to take away the conditions, it's about hitting a tennis ball and finding a way to win the match.
"When I'm looking at that and I'm watching the game, I want to turn it off and just watch a movie. It gives you a sense of boredom. There's no electricity of the body.
"There's so many athletes out there that often that's what we see and it does my head in. If you don't like it that much, leave the sport. Show some passion."