A transfer fee was not disclosed, though multiple reports in England said United will pay the Portuguese club £30.75 million (€35m, $39.2m) for the centre-back.

Lindelof still needs to agree personal terms with United, and the deal is subject to a medical and international clearance.

The 22-year-old has been linked to a move to Old Trafford since the winter transfer window as one of Jose Mourinho's top targets, though the United manager ultimately decided against a January bid after being impressed with the form of both Marcos Rojo and Phil Jones.

In November, Lindelof drew high praise from United's recently departed striker Zlatan Ibrahimovic, who said his countryman is "good enough for the big clubs out there."

Lindelof himself had suggested this week that his future could become clearer after Sweden's World Cup qualifier against France in Stockholm on Friday, a 2-1 win in which he played all 90 minutes.

He will join Eric Bailly on the United back-line, as well as Jones, the injured Rojo, and Chris Smalling, who was often criticised by Mourinho this past season.

Lindelof could be just the first addition to United this summer as sources told ESPN FC in May that Mourinho was targeting four new players during the transfer window: a centre-back, a midfielder, an attacking player and a striker.

Real Madrid striker Alvaro Morata has been reported as the top target to replace Ibrahimovic as a new No. 9, while links to Torino striker Andrea Belotti continue -- though Antoine Griezmann has said he will stay at Atletico Madrid.

In terms of outgoing United players, captain Wayne Rooney has to decide whether to fight for his place or move on. Real Madrid are no longer said to be in pursuit of United goalkeeper David De Gea, but other players around the club are the subject of speculation and interest.