Louis van Gaal has signed Sergio Romero on a three-year deal with an option of a further 12 months, the Argentina goalkeeper arriving at Manchester United on a free transfer from Sampdoria.

Romero is expected to be the No2 goalkeeper with Víctor Valdés, who has fallen out with the manager Louis Van Gaal, set to leave the club.

Van Gaal previously worked with Romero at AZ Alkmaar and he was part of the Dutchman’s Eredivisie title-winning side in the 2008-9 season. He played for Argentina in the nation’s run in the 2014 World Cup final, defeating Holland in the semi-final, when the Dutch were coached by Van Gaal.

Romero, 28, has 62 caps and may be a challenger for the No1 jersey should David de Gea leave for Real Madrid. Indeed, Van Gaal claims he was forced into signing Romero because of the uncertainty surrounding De Gea, who may still leave this summer.

“I think that in our circumstances, with the threat that David de Gea is going to Real Madrid, we have to prepare our season and I think Sergio Romero can fulfil that because you have to handle very quickly when it may happen with David de Gea,” the United manager said.

“I am absolutely delighted to join Manchester United,” said Romero. “To play for the biggest club in the world is a dream come true. Louis van Gaal is a fantastic manager and I cannot wait to get started on this new and exciting challenge in my career.”

Van Gaal added: “Sergio is a very talented goalkeeper. He was a young keeper during my time at AZ Alkmaar and I am delighted he is joining Manchester United. Sergio had a fantastic World Cup last summer in Brazil, although, that is something I have put to the back of my mind. He will be a great addition to the team and I am looking forward to working with him once again.”

Romero is United’s fifth signing this summer. He follows Memphis Depay, Morgan Schneiderlin, Bastian Schweinsteiger and Matteo Darmian.