Fritz, the 13th seed, gained a 4-6 6-7 (4-7) 6-4 7-6 (7-3) 6-3 victory over his German opponent Zverev on Centre Court prior to Djokovic’s evening match.
Zverev was aiming to reach the Wimbledon quarter-finals for the first time and did not face a break point in the opening two sets.
But Fritz, 26, became the first player to break the Zverev serve at this tournament during the third set, before edging the fourth to move the match into a decider.
Zverev was wearing a support on his left knee after slipping in the late stages of his third-round win over Britain’s Cameron Norrie, and as he faded a crucial break went the way of Fritz in the fourth game of the final set.
For Fritz, a second appearance in the last eight at Wimbledon awaits him, two years after he lost to Rafael Nadal in a five-set thriller at that stage. It will be a fourth Grand Slam quarter-final in all for him, and he has yet to go further.
Zverev had been only two games away from victory in the third set but has now fallen at the last-16 stage of Wimbledon on three occasions after experiencing the same fate in 2017 and 2021.
“It was amazing to do that on Centre Court, two sets down in front of this crowd. It’s a dream,” said a victorious Fritz, who gained only the third win of his career from being two sets behind.
“I still felt I was playing really well despite being down two sets. I was just thinking it sucked to be playing this well and to lose in straights.
“It’s a second time in the quarter-finals, but this time I felt I earned it a lot more so I’m really excited for the chance.”