Fabio Fognini used the offensive Italian word repeatedly during the three-set loss to Russian second seed Daniil Medvedev in the third round on Wednesday.
Although the world No 31 wrote in an Instagram story early on Thursday that the hot conditions in Tokyo “affected his head” and that he “used a really stupid expression toward myself”.
“Obviously I didn’t want to offend anyone’s feelings,” Fognini added. “I love the LGBT community and I apologize for the nonsense that I let out.”
However, the Instagram story was written on a rainbow background. Medvedev nearly fainted during the match, asking the chair umpire who would take responsibility if he died, and Fognini also struggled with the heat.
Fognini repeatedly slammed his racket during the loss, including after the final point, after which he left it in a court-side rubbish bin.
The 34-year-old was thrown out of the doubles tournament at the US Open in 2017 for obscene remarks to the chair umpire during his first-round loss in singles. He was then handed a suspended ban of two Grand Slam tournaments.
There have not been any reports of any fine or punishments for Fognini from the organizers of the competition.