Zverev is through to the third round, having worked with the recently-retired former French Open finalist in the lead-up to the event.
"We said that we're going to have a trial period, and in that trial period he was so unbelievably well-organized and the work has been incredible," said Zverev. "I enjoyed the practices more than I did in the last few years."
That's an important statement from the 23-year-old, who has split with high-profile coaches Ivan Lendl and Juan Carlos Ferrero in recent years, though his father, Alexander Sr., has also consistently been coaching him.
Their initial success means Ferrer will we part of Zverev's team, in person, for the clay events.
"I'm happy he's joining the team. I'm excited to have him in Europe, for the clay court season," said Zverev.
Zverev has won three Masters 1000 titles and the ATP Finals and got to the semifinals of the Australian Open at the beginning of the season—his best showing at a Grand Slam. But he has had serving problems recently and can get into trouble on his forehand, though, as Ferrer notes, his backhand is among the best on tour.
“One thing that he has said to me is if you're ever not feeling your backhand, [if] that's your biggest worry, we will just be fine. That he said to me,” Zverev said. “We worked on a lot of things. I'm not going to say what we worked on because I'm still in the tournament, but I think it'll show over the next few months.
"So far I think he's enjoying it, and he said the most important thing is to have fun with what you do. Once you have fun, you're going to be better."