Alexander Zverev didn't have to spend a lot of time on the courts in Geneva to book the semi-final as his opponent retired down 1-4 in the first set.
Zverev opted to play in Geneva to finetune his tennis ahead of a return to Roland Garros and it's been going well. He's in the semi-final playing pretty well thanks to the condition favouring his serve and style of play. This match started well as well for him with an early 4-1 lead however it was cut short as Wu retired.
The Chinese player wasn't able to continue the match and while the outcome is good for Zverev he would have liked to finish the match and build up his confidence. A good challenge awaits him in the next round though as he'll face either Ruud or Jarry. Either player is good on clay and Ruud is the defending champion.