Dutch football journalist Marcel van der Kraans is sure the 20-year-old centre-back will team up with Erik ten Hag despite suggestions Timber could stay on at Ajax.
Van der Kraans added that Timber's arrival could lead to the Red Devils adopting a style similar to rivals and Premier League champions Manchester City.
"I'm absolutely convinced he's going to get Timber in at Manchester United," Van der Kraans told talkSPORT. "I know the player's said he has to think about leaving Ajax… I think it was all political talk.
"I think he's already made his mind up and he will join Ten Hag.
"He'll be a really important player for Ten Hag because he can change the build-up from the back. He can change the style.
"If you look at when Rio Ferdinand joined, he was a footballing central defender. Ten Hag will never play with two Harry Maguires. He will want to have a real footballing player in central defence to start the build-up.
"Ten Hag will want to play on the half of opponents, just like Pep Guardiola. He's a massive fan of Pep. I would almost think that there will be two teams with the same playing style in Manchester."
A mammoth task awaits new Red Devils boss Ten Hag, who takes over a Manchester United side that hasn't won the Premier League in nine years and lasted tasted silverware in 2017.
Ten Hag has also been warned against falling into the same trap of being 'too Dutch', like former Man United boss Louis van Gaal.
"I think Ten Hag will have to adapt," Van der Kraans added. "That's been my main objection to Dutch managers going to England - you don't know what the Premier League is about until you get there.
"I think every continental manager who's never played in England gets a culture shock once he gets there.
"That has been the problem for Louis van Gaal as well. Louis van Gaal's a great coach, he's got loads of funny habits and he has a very outspoken Dutch way of dealing with the media.
"He's a good coach but he wasn't the right man for Manchester United. He wanted to be too Dutch but you can't be too Dutch.
"I hope Erik ten Hag has learned from that and he's seen that and he will adapt easier."