"I hope De Gea stays"

De Gea missed the first two matches of United's US tour with an undisclosed injury that fuelled speculation about his possible transfer to Real Madrid, who want him to replace Iker Casillas.

However De Gea returned to face Barcelona at the Levi's Stadium to play a key role in United's 3-1 friendly victory, pulling off a couple of important saves in a commanding display between the sticks.

One stop, when he denied Sergi Roberto an opener for Barcelona after only five minutes, proved crucial as United swept upfield and scored two minutes later.

Van Gaal expressed his admiration for De Gea's ability to return to form despite an injury lay-off.

"In spite of his injury, he doesn't train for one week, he showed his quality in this game," van Gaal said.

"The first chance was for Barcelona and when you stop the first chance you can score the first goal and that is always a difference in the game."

Van Gaal admitted he was keen to keep De Gea but said ultimately the decision may be out of his hands.

"Yes of course I do hope De Gea shall stay, but in this world of football you never know," he said.

Van Gaal was also full of praise for the performance of United's de facto second string, who replaced his starting eleven just after the 60-minute mark.

Van Gaal had sharply criticised the same group of players after a lacklustre performance against the San Jose Earthquakes on Tuesday.

"I was very happy with the reaction of the youngsters because they were more aggressive and that is what I want always," van Gaal said.

"It was a team with the spirit, we created chances, we scored two goals with the youngsters so I'm very happy."

The Dutchman also praised the performance of forward Adnan Januzaj, who scored United' third goal.

"Adnan Januzaj was very good, because he gives always an option for his midfielders and defenders," he said. "He scored a wonderful goal."