Manchester, July 27 (IANS): English football club Manchester United on Monday roped in Argentina goalkeeper Sergio Romero as David de Gea is still uncertain about signing for the Premier League team.

Romero left Italian club Sampdoria and was a free agent. United lured him to sign a three-year deal to replace Spanish reserve goalkeeper Victor Valdes, who has been asked to leave by manager Louis van Gaal.

"We have to prepare our season with the threat that David de Gea is going to Real Madrid," van Gaal was quoted as saying by BBC.

De Gea is into the final year of his contract with United and is wanted by Real Madrid. If at all de Gea stays at Old Trafford, the Dutchman said Romero would bring in healthy competition.

"You always need competition. When I see that a player is better than the player in the line-up, he shall play the next match," said van Gaal.

Romero has 62 international outings to his credit and was instrumental in knocking van Gaal's Netherlands out of the World Cup by saving two spot-kicks in 2014.

He became United's fifth signing of the summer, following in the footsteps of defender Matteo Darmian, midfielders Bastian Schweinsteiger and Morgan Schneiderlin and striker Memphis Depay.

Asked about Romero, the manager said: "He is a very dominating goalkeeper, he dominates the 60-metre area. His stature is also tall and he gives a lot of confidence to the players."