Manchester United's new manager officially starts training sessions

Netherlands' coach Louis van Gaal [AFP PHOTO/EVARISTO]

Manchester United players have already had a taste of Louis van Gaal's methods after the new manager, who is officially unveiled in the role on Thursday, ordered double training sessions just two days into the pre-season.

Van Gaal, smiling and looking relaxed after arriving from his stint as Netherlands manager at the World Cup, was given a tour of the Carrington training facility by his new assistants, recently-retired United star Ryan Giggs, and Albert Stuivenberg.

The Dutchman introduced himself to the players individually but it is understood that he is waiting for the return of those enjoying post-World Cup breaks, including striker Wayne Rooney, before he addresses the squad as a whole.

Van Gaal, 62, a noted disciplinarian, has been asked to make United a force again after last season's disappointing campaign under David Moyes in which they finished seventh and failed to secure European football.

In Brazil, where he guided the Dutch to third place, he said he was aiming to instil the same team unity at Old Trafford.

"I hope the group in Manchester will become like this one," he said after the Dutch ended their World Cup campaign with a 3-0 victory over Brazil.

"We have to sing from the same hymn sheet."

The squad containing new signings Ander Herrera and Luke Shaw, who were brought at a combined cost of £56 million ($95.88 million), depart for the United States for a pre-season tour on Friday.

Van Gaal, who has won titles with Ajax, Barcelona, Bayern Munich and AZ Alkmaar, will take charge of a United match for the first time on July 23 against the Los Angeles Galaxy.

Elsewhere, Japan's Shinji Kagawa has vowed to prove his worth to van Gaal after a disappointing World Cup plunged his future into further doubt.

"I feel incredibly excited," Kagawa told reporters at Tokyo's Haneda airport on Thursday before leaving for England.

"It's a new start and I feel re-energised. It's up to the players to get the results we need. I have a strong desire to do well."

Kagawa, an instant hit for United after being signed by Alex Ferguson from German Bundesliga side Borussia Dortmund in 2012, found himself largely frozen out last season under the troubled reign of David Moyes.

"I'll look more closely at my game and accept the challenge filled with passion," insisted the 25-year-old Kagawa, who gave three lacklustre displays at the World Cup as Japan finished bottom of their group.

Van Gaal is expected to decide quickly whether to offer Kagawa, who has two years left on his contract, an extended deal.

"It was the most disappointing experience of my life," Kagawa said of Japan's meek exit from Brazil. "How I can use that as a plus will depend on how hard I work."