Speaking at his official unveiling press conference, the new Atalanta head coach revealed his main concern had been how the Brazilian would react to staying at the club after appearing to have one foot out of the door.
"Ederson will return to the squad. My worry was what state of mind the boy might be in staying here with us. Instead, Ederson has shown maturity and a great desire to stay: he will be a pillar of this Atalanta side," Sarri said.
The move to Old Trafford had appeared close to completion, with Ederson even having completed part of his medical before Manchester United pulled out following a second round of tests, reportedly related to a past meniscus issue.
He returns to Bergamo to work under Sarri, who was appointed as Atalanta's new head coach this summer and used his first press conference to lay out his broader vision for the club, alongside plans for two key positions already reinforced by the club's transfer business.
Asked about the signing of Gianluca Gaetano, Sarri praised the club's recruitment work.
"It was a great gift from the director. And overall the season will be long and there will also be alternative options in terms of formation, like a 4-2-3-1, hopefully so we can play as many matches as possible. We'll see, we have plenty of solutions," he said.
Set a question about his ambitions for the club, Sarri was candid about the challenges ahead while remaining confident in his methods.
"The objective is to become a competitive team. I know the first few days will be difficult, but I'm convinced we can do well. Even at Napoli we had difficulties at the start, and then we know how things turned out," he said, drawing on his own experience of building a project from the ground up.
Sarri was also asked for his early impressions of Atalanta's Under-23 side.
"We'll assess things at the end of the transfer window, but the boys I'm currently coaching in this period — I can guarantee some of them are capable of playing in Serie A," he said, hinting that academy graduates could yet play a role in his plans for the season ahead alongside the more experienced additions to the first-team squad.
It was a wide-ranging first appearance in front of the media for the former Napoli, Chelsea and Lazio coach, who takes charge of an Atalanta side aiming to remain competitive on multiple fronts following the departure of his predecessor.