His 2022 season lasted until the semi-final of the French Open against Rafa Nadal (36), when he suffered an ankle injury that would sideline him for months.
A bone edema kept him off the court for the remainder of the season and he arrived in Australia with a realistic view about his chances of going deep in the year's first Grand Slam.
He had to come back from two sets to one down to beat Peruvian Juan Pablo Varillas (27) in the opening round on Tuesday but overcoming a second lucky loser on Thursday was beyond him and Mmoh joined an American charge into the third round.
"I didn't have any expectations. I didn't have any goals, and it was a good test for me," Zverev told reporters after the 6-7(1) 6-4 6-3 6-2 defeat.
"I played a five-setter, and I know where I am physically. That's about it. I guess I still have a long way back to where I was."
Zverev, runner up at the 2020 US Open and number two in the world last year, said he had fully recovered from his injuries but still had a way to go to get back to full fitness.
"My foot is healthy, but I'm not at the physical level that I was," he said.
"I'm not as fast. Definitely my conditioning is not as good as it was. So I think I still have a long way to go to there."
Zverev kicked off his season at the United Cup team competition, losing both of his matches, but said his time in Australia had given him some encouragement.
"I think the last weeks I was getting better and better, and that is something very positive for me," he said.
