The Frenchman fell at his baseline, then launched a ridiculous topspin forehand from the set of his pants.
The Pole injured his right knee while falling at Wimbledon in the third round.
Defending Hamburg champion Alexander Zverev won his opening round despite a lingering knee injury.
The Hall of Fame Open will be revamped into a joint ATP Challenger and WTA 125 level event next summer, scheduled for the second week of Wimbledon.
The BJK Cup Finals and the Davis Cup Finals will be played at the same venue in November.
Audience for Wimbledon men's and ladies' finals increased compared to 2023.
The field is set for tennis at the 2024 Paris Olympics.