The 27-year-old will face unseeded American Mackenzie McDonald in the fourth round on Monday.
"I don't know how far I will go in the tournament but I'm confident", Del Potro said. "It makes me stronger mentally".
Victory was in sight for Zverev after he built a 5-2 double-break lead in commanding rallies before settling the contest with a rapid serve after three hours and 12 minutes. "If I feel better, it might be two.' I thought I'd go out there and try". "I was extremely negative yesterday and just needed to come out with a very different state of mind and different approach today to have a better chance than I had yesterday".
The same was true for Roger Federer, who saw off Germany's Jan-Lennard Struff in straight sets to reach the second week of the tournament for the 16th time in his career.
But then came one injury after another and a slide to 589th a year ago because of a lack of matches. However, as the son of a Latvian oligarch, money has never been a motivating factor for one of the tour's more eccentric characters, and he has the big-match experience having made the French Open semi-finals in 2014. "He's obviously had good wins through these last three matches here".
The 21-year-old from Germany is ranked at No 3 in the world but has not yet won a Grand Slam.
India, England match to be a cracker in the decider
The character they showed is something we are really proud of. "This series for us has produced three different performances". Unfortunately for England , the Indian batsmen also enjoyed the bright sunshine and short boundaries in Bristol .
"Yesterday was tough for several reasons, I had a stomach virus, went to bathroom at the end of the second set and threw up, and last night I didn't eat anything", Zverev admitted.
'I showed in Paris and other matches that I don't really get exhausted in five-set matches. "There was no going back".
German fourth seed Alexander Zverev wilted in 33-degree heat and crashed out in the third round on Saturday.
The Wimbledon tennis tournament is well-known for its strawberries and cream.
The 4 seed is scheduled to lock horns with Latvia's Ernests Gulbis next.
Gulbis has earned 115 ATP ranking points for advancing to the third round of Wimbledon, where he will take on the victor of the second-round dual between Taylor Fritz (United States) and Alexander Zverev (Germany).