Zverev, the world No.4, was beaten in three sets 3-6 7-6 6-4 by Del Potro in China in the third-round clash and he admitted afterwards that he'd come up against an in-form opponent, while he stressed he had done plenty right in the game as well.
"I think he played a great match, maybe one of the best of the season," Zverev said. "I think we both played pretty well from the baseline. I don't know what I could have done better, but for me, in my eyes it's impossible to lose a match where I get broken one time and I still lose it.
"In my eyes I did a horrible job maybe returning or getting the points going on his serve. But apart from that, I think from the baseline and me serving, I think I did well. I had - you know, the game that he broke me, I was up 40-15 or 40-Love on my serve."
He added: "I was just unfocused there. I feel like I could have done great in this tournament if I get through this match."
Zverev, 20, has already qualified for the ATP World Tour Finals at the O2 next month but is yet to decide if he will play in the NextGen Finals in Milan, the new ATP tournament featuring the world's top 21-and-under singles players across the ATP World Tour season.