Louis van Gaal reveals how he instructed Marcus Rashford to Manchester United debut double

Rashford scored twice after replacing Anthony Martial in the starting XI

Marcus Rashford scores his second goal of the game (EPA)

Louis van Gaal has revealed he instructed Manchester United debutant Marcus Rashford to run less if he wanted to score in his first appearance for the club.

Rashford, just 18, was drafted into the starting XI after United suffered another injury, when £36million Anthony Martial was injured in the warm-up.

The injury leaves the Dutchman with 14 players currently unavailable.

Rashford didn't exactly look out of place in the first-half but didn't have any goal scoring chances.

Van Gaal revealed he gave the striker a half-time pep talk which led to the teenager scoring twice in the second-half as United won 5-1.

"Unbelievable, in the first half he ran too much, too much on the sidelines, and I said at half-time, 'You have to be within the width of the goal and you shall score,' and you see he scores two goals, it is fantastic for him," he told BT Sport

"It was a great performance, I think the fans shall have enjoyed our attacking football."

On Martial, Van Gaal added: "I think he is smart and wise to step out, because it was not a rupture, it was a tight hamstring," he said. "I don't think it is very heavy."

Depay, who impressed all evening on the left flank, wrapped up the victory with a fine goal late on and he was satisfied with his evening's work.

"Tonight was good, we enjoyed it on the pitch and you could see that," said the winger. "We are very happy to go through, we have to keep the spirit in the team and look forward to Sunday."

United host Arsenal at Old Trafford on Sunday in the Barclays Premier League and Van Gaal is hoping for a repeat performance.

He added: "The players have to recover, we have to cope with that and I hope it shall be a very good match."

Additional reporting from PA