World number two Novak Djokovic said Andre Agassi will be his new coach after the Serb lost in the Italian Open final to Alexander Zverev.
The 12-time Grand Slam winner parted company with his entire coaching team earlier in May.
Former world number one Agassi will be with Djokovic in Paris for the French Open, which starts on 28 May.
The news was confirmed after German Zverev, 20, stunned Djokovic 6-4 6-3 to win in Rome.
In the women’s event, Ukraine’s Elina Svitolina triumphed with a 4-6 7-5 6-1 win over Romania’s Simona Halep.
‘No long-term commitment’ – Djokovic
Djokovic had said the “shock therapy” of splitting with his backroom team, including Marian Vajda – who has been with him through almost all of his career – would help achieve better results.
Boris Becker, a six-time Grand Slam winner, left in December after three years as the 29-year-old’s main coach.
Now he has brought in American Agassi, who retired in 2006 after a career which yielded eight Grand Slam titles wins.
“I spoke to Andre the last couple weeks on the phone, and we decided to get together in Paris. So he’s going to be there,” said Djokovic.
“We’ll see what the future brings. We are both excited to work together and see where it takes us.
“We don’t have any long-term commitment. It’s just us trying to get to know each other in Paris a little bit.”
BBC tennis correspondent Russell Fuller
Agassi has no top-level coaching experience, but Djokovic could not have made a more exciting choice. The 47-year-old remains hugely popular; a charismatic, and sometimes enigmatic, true great of the game.
Having benefitted from the counsel of Boris Becker (Djokovic won six Grand Slam titles in their three years together), he is now hoping to build a relationship with Agassi, who like Djokovic, knows how it feels to win each of the Grand Slams.
If there is to be a more permanent arrangement it is likely to revolve almost exclusively around the Grand Slams. Agassi and wife Steffi Graf have two teenage children, he is heavily involved in his charitable foundation and has indicated in the past that he does not want to be away from his Las Vegas home for too long.
Zverev youngest Masters winner for 10 years
At 20 years and one month, Zverev is the youngest Masters event champion since Djokovic himself won the 2007 Miami Open.
Fearless Zverev, currently ranked 17 in the world but now set to move into the top 10, dominated from the start.
He did not face a break point and broke the 12-time major winner in the first game and twice in the second set.
Djokovic received a code violation for an audible obscenity in the seventh game of the second set, and later double-faulted to hand Zverev match point.
A long backhand by the Serb, who will celebrate his 30th birthday on Monday, subsequently ensured victory to his highly-rated opponent.
Djokovic’s semi-final win over Dominic Thiem had hinted he was close to recovering his best form after a poor year, culminating in the departure of his entire coaching staff earlier this month.
But Zverev was composed throughout and won in one hour and 21 minutes.
“It’s such an honour being on the court against one of the best ever players,” said Zverev after his victory.
“If I have half the career Novak has had, I will be just fine.”
Referring to the French Open, the second Grand Slam of the year, which begins on 28 May, he added: “I’m sure he will be one of the favourites in Paris.”
Djokovic will need to raise his game having hit 27 unforced errors to his opponent’s 14, but hinted at a big future for the German.
“You are definitely on a great path. You played fantastic and deserve it,” he said.
Victory for in-form Svitolina
Svitolina fought back from losing the first set to win her fourth title of the year.
The 22-year-old is currently ranked 11th in the world, but will return to the top 10 when the rankings are updated on Monday.
Halep, 25, who won the Madrid Open last week, rolled her ankle when leading 5-2 in the first set, but managed to take it 6-4.
The world number four had her ankle strapped in the second set, which Svitolina took 7-5.
The third set was a one-sided affair as Svitolina won 6-1 in 30 minutes.
Svitolina, who also called for a trainer in the second set, adds her Rome title to victories in Istanbul, Dubai and Taipei City.