Ivanisevic, who previously coached 24-time Grand Slam champion Novak Djokovic over six years, joined forces with Tsitsipas in May, the Greek looking to bring an end to a tough few years that saw him struggle at major tournaments.
Tsitsipas retired 72 minutes into his first-round Wimbledon clash against qualifier Valentin Royer – extending a barren run of Grand Slam form, having won just one match in the three majors so far this season.
Ivanisevic issued a brazen response, saying he has “never seen a more unprepared player” than the former world No. 3, adding that he – at 53 years of age – is “three times fitter” than Tsitsipas.Speaking to Croatian media outlet Gol, Ivanisevic said his criticism affected Tsitsipas but urged the 26-year-old to work hard towards being “physically and mentally prepared”.
“Well, it affected him a little because every tennis player, every athlete, when their ego gets a little inflated, doesn’t like criticism,” Ivanisevic said.
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“Anyway, I told him: tennis is an individual sport. To play on the court, you have to be physically and mentally prepared. He wasn’t mentally or physically prepared at Wimbledon. Back problems, a million problems. So it’s a long road, there’s no magic wand, no magic tricks, you have to work.”
Tsitsipas is considered among the men’s tennis players in the “sandwich generation” – who enjoyed great success in the waning careers of Rafael Nadal, Roger Federer and Novak Djokovic – but struggled to maintain their form upon the emergence of the rising stars in the game, such as Carlos Alcaraz and Jannik Sinner.
His form has tailed off in recent years, in part due to injuries, and he has suffered recently with a long-term back issue.
Tsitsipas’ victory against Tomas Martin Etcheverry in the French Open first round is his only Grand Slam win this year. He was ousted two days later in Paris by the unseeded Matteo Gigante.
But the 2023 Australian Open runner-up has appointed a coach of great pedigree in Ivanisevic. The Croatian guided Djokovic to 12 of his 24 Grand Slam titles – with the Serb’s serve notably improving during that time. 
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Patrick Mouratoglou, Tsitsipas’ former coach who is now working with Naomi Osaka, criticised Ivanisevic for his comments.
“Goran going to the press and criticising his player is not coaching,” he said in a video published on Instagram.
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