Once an up-and-coming player on grass having won the Stuttgart Open and Queen's Club Championships twice, the Italian missed last year's Wimbledon after testing positive for COVID-19 on the eve of the tournament.
Injuries have also seen him fall from a career-high sixth in the world to number 38.
But in the first two rounds at Wimbledon this year, Berrettini sounded out a warning after prevailing in a three-day battle to beat compatriot Lorenzo Sonego and with a straight sets win over 15th seed Alex de Minaur without dropping serve.
"What happened last year is something that I think didn't heal yet. It's a really sharp pain if I think about it," Berrettini told reporters.
"I probably was in the best shape in my career, especially feeling great on grass. I wanted to enjoy the tournament, it's such a special tournament for me.
"Not being able to play was something that, even when I was better physically, was really tough mentally to overcome. That's why I'm here this year, because I missed last year. I was really sad."
German 19th seed Zverev is on his own road to redemption after the former world number two injured his ankle in the French Open semi-finals last year, which required surgery and a lengthy rehabilitation.
SEMI-FINAL RUNS
Now ranked 21, Zverev has built a head of steam with semi-final runs at Roland Garros and at the grasscourt tune-up tournament in Halle but said he was no favourite against the resurgent Berrettini.
"I think he's one of the best grasscourt players that we have. In the last few years he's made a Wimbledon final, he's won Queen's two times. I think he's an incredible player on grass," Zverev said.
"I think he found his form again, he's playing very good tennis ... I think (grass is) his favourite surface, probably my least favourite.
"It's going to be an entertaining match, it's going to be a match that maybe the crowd is also looking forward to a little bit. Hopefully it's going to be fun to play."
World number one Carlos Alcaraz has yet to drop a set this week and opens proceedings on Centre Court when he plays Nicolas Jarry before Ons Jabeur faces former U.S. Open champion Bianca Andreescu.
Defending champion Elena Rybakina is also on Centre Court later when she faces British hope Katie Boulter.
"For sure the atmosphere is going to be a bit different. The crowd won't be supporting me that much," Rybakina said.
"She's a tough player. Her game is aggressive, also she has a good serve. It's going to be a tough one but I'm going to watch a bit of her matches and talk with the coach about the tactics."
