As the Frenchwoman walked back onto court after a medically induced heat break, the 28-year-old didn't realise she'd accidentally put her shirt on backwards.
Cornet remonstrated with the chair umpire about the length of time it had taken her to walk back from the designated cool-down area to court 13.
After placing her bag down, she strode into the shadows at the back of the court, put her racquet between her legs, turned her back to her opponent and the crowd and quickly lifted her top off, briefly revealing a black and red sports bra.
Shortly after she'd flipped it back into place, umpire Christian Rask issued her with the penalty.
Commentators and social media were swift in their condemnation of the call.
Alize Cornet came back to court after 10 minute heat break. Had her fresh shirt on back to front. Changed at back of court. Got a code violation. Unsportsmanlike conduct..... 😳— judy murray (@JudyMurray) August 28, 2018
But the men can change shirts on court. https://t.co/sCN4KDXYTb