After the match, Zverev said: 'Here definitely the conditions are different. I feel like the ball flies more through the air and is tougher to control. So I had to string my rackets way tighter, which gives you a different feel on the racket. But we're tennis players. We have to adjust every single week.'
The 21-year-old will be back competing next week in Cincinnati looking for a better result, and especially a less frustating end.