David de Gea
David de Gea continues to be linked with a move to Real MadridGetty Images

Manchester United manager Louis van Gaal says David de Gea is not guaranteed to start the season as the club's number one after Argentina international Sergio Romero joined on a three-year deal.

De Gea's performances last term proved hugely influential as the club qualified for the Champions League, with the Spanish international among the six nominees for the PFA players' player of the year award.

The addition of Romero comes after Van Gaal told Victor Valdes he could leave United after six months at Old Trafford, while the Dutch coach also fears that De Gea will join Real Madrid this summer.

But in the event that De Gea remains, Van Gaal says he may not begin the campaign as the club's number one, following the arrival of World Cup runner-up Romero. "In our circumstances, with the threat that De Gea is going to Real Madrid, we have to prepare our season and I think Sergio Romero can fulfil that," Van Gaal said according to Goal.com.

"You have to handle the situation very quickly if [a move to Real Madrid] happens with De Gea. I have of course spoken with Sergio and also with David and, with me, always the best shall be in the line-up. So you have to fight and I think in a top club as Manchester United, you need always competition."

Real boss Rafael Benitez has been consistently coy over the prospect of signing De Gea this summer, and according to AS said last week: "I don't know. He's not here, he's not a Madrid player and so I don't know. I don't speak to Van Gaal every day. I have a goalkeeper for every game and I am happy."

Following the departure of club legend Iker Casillas, Real signed Kiko Casilla from Espanyol. However that has done little to dampen United's fears that De Gea – who is out of contract in the summer of 2016 – could leave before the start of the new term.