Sanchez landed in Manchester earlier today after chartering a private jet from London.
The Arsenal player will have a medical at Carrington before signing off on his £500,000-a-week contract.
Sanchez was seen sat in the back of a car, being driven to United’s training complex.
His move to Manchester United comes as Henrikh Mkhitaryan arrives in London to complete his part in the swap deal with Arsenal.
United are expected to announce Sanchez’s signing by Monday.
Sanchez’s whereabouts have been kept secret in recent days, with reports he had driven up to Manchester on Friday night to agree terms with the club.
But he left the capital this morning to head up north in a private jet.
Jose Mourinho was asked about the player following United’s 1-0 win at Burnley yesterday.
He said: “Mr Woodward is working hard, everybody is giving everything they can, and I think they will be successful.
“Expect soon or never. So close, so close, so close, if it doesn’t happen it’s not going to happen.
“I know my people are doing absolutely everything they can. I think they will be successful.”
There are still 10 days remaining of the transfer window but Manchester United are not expected to complete any more deals.
Arsenal, meanwhile, are chasing Pierre-Emerick Aubameyang as a direct replacement for Sanchez, with Mkhitaryan unlikely to fill in the forward position the Chilean took up in north London.
Express Sport understands a £55m bid is needed to get Dortmund to the negotiating table over Aubameyang.