Sir Alex Ferguson has warned big-money summer signing David De Gea he isn't guaranteed to be Manchester United's first-choice goalkeeper.

The Spaniard joined United from Atletico Madrid after playing for Spain at the European Under-21 Championship and was expected to fill the void left by Edwin van der Sar's retirement at the end of last season.

But with January arrival Anders Lindegaard and youngster Ben Amos making a series of excellent stops in United's 7-0 pre-season romp against Seattle Sounders, they proved they will provide De Gea with plenty of competition.

Ferguson said: "Obviously we have signed David de Gea as the main choice I would imagine.

"But Anders Lindegaard and Ben Amos have probably said to themselves they have an opportunity with Van der Sar retiring.

"It is an open door for me.

"De Gea will play on Saturday against Chicago but they will all get their fair share of games and the decision on who starts the season will depend on how De Gea settles."

While both goalkeepers used caught the eye, striker Wayne Rooney was the undoubted star of the show against Seattle.

Introduced as a second-half substitute, the England international wasted no time in making his mark, finding the net three times within the space of 21 minutes to signal his well-being ahead of the new campaign.

"It is nice he scored," said Ferguson.

"We are pleased for all the goalscorers but three goals is a nice start for him.

"He has worked hard. He has done really well in training."

Michael Owen, Mame Biram Diouf, Park Ji-sung and Gabriel Obertan also found the net and Ferguson wants to see a similar spread of firepower across the season as a whole.

"Last year we depended on three players for our goals, so that was good," he said.

Although De Gea's fellow new-boy Ashley Young has not managed to score any of United's impressive two-game haul of 11, the former Aston Villa man has settled in well and already looks as though he will make a positive contribution to United's quest for honours.

"I am just delighted to be here and get myself on the pitch," he said.

"No disrespect for the Villa boys but as soon as I heard of Manchester United's interest, I just wanted to get the deal done and start training.

"I can play left, right, off the front striker or as a main striker, so I just have to concentrate on my own game and wherever I am picked, do myself justice.

"The manager bought me for a reason, to get assists and goals and work hard for the team. If I can do that every time I am selected, my job is done."

It is the first time Young has been exposed to the sheer size of the club he has now joined. And while the reception United has received does not compare to an Asian tour, the sight of fans maintaining a constant presence outside the team hotel is novel.

"This is fantastic for me," he said. "You come to the United States and see the number of fans outside the hotel every day.

"It is crazy and just shows how big the club is.

"For me to be part of that is fantastic."