Bernard Tomic's French Open preparations took a hit after retiring just eight minutes into a first-round Internazionali d'Italia match against Benoit Paire.
Australian Tomic was 2-1 up in the first set against Paire before retiring after a short consultation with a doctor.
Tomic, ranked 22 in the world, said he could not cope with the heat in the Italian capital.
"I was feeling bad all night," Tomic said.
"I couldn't play with the heat. I felt so, so bad and I felt like I was going to collapse. It was the best thing for me to do to retire. The main thing is to get it out of my system."
Tomic has crashed out at the first hurdle of his last four tournaments, including in controversial fashion at the Madrid Open.
The 23-year-old appeared to tank when facing three match points after holding racquet the wrong way around in a first-round clash against Fabio Fognini.
Players such as Novak Djokovic criticised Tomic's approach, while his response also caused anger among the Australian sporting community, when he told the Gold Coast Bulletin: "I don't care about that match point - would you care if you were 23 and worth over $10million?"
Those comments also drew a reaction from Australia's chef de mission for the upcoming Olympic Games in Rio, Kitty Chiller, who said Tomic was under close watch ahead of the upcoming nominations for the tournament.