David Ferrer has passed the test.
Alexander Zverev confirmed he has hired former world No. 3 Ferrer as his new coach.
Watch: Federer's Rooftop Rally
The pair had been working together on a trial basis in recent weeks. Zverev, who split with Hall of Famer Ivan Lendl last season, said he has a good rapport with former French Open finalist Ferrer.
"The test phase is over. We are together, a partnership," Zverev told the media at the UTS exhibition event in Nice. "We understand each other incredibly well and are now a team.”
The 38-year-old Ferrer will serve as the seventh-ranked German's co-coach along with Zverev's father, Alexander Zverev, Sr.
“David and my father are both my head coaches now," Zverev said. "My dad doesn't get any younger either. Both are extremely important in the team."
Zverev won five of eight career meetings vs. Ferrer, including defeating the Spaniard in his final career ATP match in Madrid last May.
Widely regarded as one of the hardest-working men in the game, Ferrer retired with 734 career match wins, 27 titles and more than $31 million in prize money.
Prior to working with Lendl, Zverev was briefly coached by another former world No. 1 Juan Carlos Ferrero.
Ferrero and Zverev split after the 2018 Australian Open with the former French Open champion critical of some of Zverev's work habits.
“Let’s say it was a way of to be out of the court [that caused the split]. I think I had different ideas what is the way to be a professional out of the court like eat, have rest, how to deal with rest of people of the team," Ferrero told the Double Bagel podcast. "We had differences over there and at the end, we thought it was the best not to continue.
“He needs to first open his ears, and to listen to people who have more experience than him in what he needs. But obviously, he will grow up and be 24 or 25 and I think he will think these things by himself.”
Photo credit: Mutua Madrid Open Facebook