Steve Darcis, the world number 135 who stunned Rafael Nadal at Wimbledon, pulled out of the tournament with a shoulder injury on Wednesday.
"Had to withdrawn after a win like this!?THE most difficult thing i had to do!!!#," tweeted the 29-year-old Belgian.
Darcis had been due to face Poland's Lukasz Kubot in the second round later Wednesday.
Earlier in the day, his coach admitted that Darcis, who suffered the injury when he fell over against Nadal, would be forced out.
"There is a 99% chance that Steve will not play his second round match," Reginald Willems told sudinfo.be.
"Sadly, this is sport. The greatest moment of his career is followed by the greatest disappointment."
Darcis inflicted Nadal's first ever opening round defeat at a Grand Slam with his stunning straight sets win on Monday.
Kubot will face either Benoit Paire or Stephane Robert for a place in the last 16.