Manchester United's Danny Welbeck celebrates his opening goal against the LA Galaxy during their Chevrolet Cup match at the Rose Bowl in Pasadena, California on July 23, 2014 © Getty Images

Ander Herrera saw a long-range effort tipped over by Brian Rowe early on, but the Los Angeles goalkeeper had no chance of keeping out Danny Welbeck's strike in the 12th minute as the forward found the back of the net via the inside of the post.

It was one-way traffic for most of the first half, but the visitors had to wait until the 42nd minute for their second of the match as Wayne Rooney fired home from the penalty spot after Baggio Husidic had handled inside the box.

Manchester United's Ander Herrera passes against the LA Galaxy during their Chevrolet Cup match at the Rose Bowl in Pasadena, California on July 23, 2014 © Getty Images

Rooney then made it 3-0 just before the break with a simple finish from close range after Tommy Meyler had made a crucial mistake inside the box.

Van Gaal made nine changes at the break, with the likes of Rooney being removed to make room for fringe members of the squad, but the onslaught kept on coming from United.

Reece James combined well with Ashley Young for the fourth goal, with the 20-year-old collecting the pull-back before finding the bottom corner.

Chances continued to be created as the hosts struggled to restore order, with Herrera seeing a header saved moments before Shinji Kagawa curled the ball just past the post.

James claimed his second of the night after reacting quickest to a miss from Young to tap the ball home.

Young's luck soon changed as he became the third player to score a brace by taking the ball past the Galaxy shot-stopper to convert United's sixth, before completing the scoring with an emphatic finish after breaking free of the Los Angeles defence.