Ronaldo is rated as one of Europe's brightest young stars Kleberson moves to Man Utd

The 18-year-old forward, who has been awarded the number seven shirt formerly worn by David Beckham, becomes the fourth summer signing made by the Premiership champions, with Brazil World Cup winner Kleberson making it a fifth later on Tuesday.

The club made the announcement to the Stock Exchange and have agreed a five-year contract with the player.

Ronaldo said: "I am very happy to be signing for the best team in the world, and especially proud to be the first Portuguese player to join Manchester United.

He is one of the most exciting young players I've ever seen

Sir Alex Ferguson

Eric Djemba-Djemba, David Bellion and Tim Howard are manager Sir Alex Ferguson's other summer signings.

Ferguson claimed an agreement had been in place to sign the player "months ago", but the Red Devils quickened their pursuit when it became clear other clubs were also chasing him.

He said: "We have been negotiating for Cristiano for quite some time, but the interest in him from other clubs accelerated in the last few weeks so we had to move quickly to get him.

RONALDO FACTFILE Full name: Cristiano Ronaldo dos Santos Aveiro 1985: Born in Madeira, 5 February 2002: Makes debut for Sporting Lisbon and scores twice 2003: Linked with Liverpool and Chelsea but completes move to Man Utd

"He is an extremely talented footballer, a two-footed attacker who can play anywhere up front: right, left or through the middle."

Ronaldo was inspirational in Wednesday's friendly against United - creating two of the goals as Sporting won 3-1.

Ferguson added: "After we played Sporting last week the lads in the dressing room talked about him constantly, and on the plane back from the game they urged me to sign him - that's how highly they rated him.

Ronaldo impressed for Portugal at the European Under-19 Championships in Liechtenstein.

Liverpool and Chelsea were also reported to be interested in the player, but they have been beaten to the punch by United.

Ronaldo is set to be unveiled by the Premiership champions on Wednesday, alongside £6m Brazilian World Cup winner Kleberson.

The Atletico Paranaense star was granted a work permit on Monday and signed on Tuesday to become the first Brazilian to play for the Old Trafford club.