Mercedes' technical boss says it's "a shame" the Brackley based team is losing Nyck de Vries.
The Dutchman, whose one-off debut for Williams this year was due to his role as Mercedes' official reserve, has been signed up by Red Bull's second team Alpha Tauri for 2023.
Franz Tost, Alpha Tauri boss, denies that Max Verstappen's recommendation that Red Bull snap up the 27-year-old rookie was the key to his 2023 signing.
"No, this was not necessary," he said, insisting that de Vries' debut drive at Monza was the real key.
"He drove a fantastic race, did not make any mistakes, therefore it was an easy decision to take him," added Tost.
The Austrian said he doubts that de Vries might get an early start at Alpha Tauri this year in the form of Friday free practice outings.
"I don't think so because he still has a contract with another team," said Tost. "I hope that we can see him in Abu Dhabi in the young driver test."
That will be up to Mercedes.
"What I see is a really nice guy, but a guy that's very knowledgeable, who understands the sport, understands engineering in the car," Mercedes' technical boss Mike Elliot said.
"I think for us as a team, it's a shame to see him go somewhere else but at the same time we're really pleased for him," he said.
"It's nice to see a driver with the talent he's got getting that opportunity."
De Vries may now be hoping that his Alpha Tauri opportunity for 2023 might even result in a promotion to Red Bull Racing after that - pairing him with fellow Dutchman and friend Verstappen.
"It's nice for the Dutch press that two drivers from your country will soon be active," Red Bull's Dr Helmut Marko told De Telegraaf newspaper.
"Our marketing department is less happy about it, but for me it's all about performance."
Therefore, an all-Dutch Verstappen-de Vries lineup in the future is not ruled out.
"That is for the future," Marko insisted. "Will the moon rise tonight or not? Who can say. Nyck just has to perform now.
"He's committed, he had a dip in the past, but he fought back. He knows how to fight."
Marko says de Vries could even find himself in a position of leadership at Alpha Tauri even though Yuki Tsunoda, who is five years younger, is the established team driver.
"Of course Alpha Tauri will benefit from Nyck's technical background," said the 79-year-old.
"He has been able to drive several Formula 1 cars this season, so it's great that he has that experience on board.
"With his personality and experience, Nyck should lead the team."
