Manchester United captain Nemanja Vidic was a surprise absentee as the Premier League champions prepared to fly out for their pre-season tour of east Asia and Australia on Wednesday.

Vidic was missing from the 19-man United squad that were due to set off on Wednesday, with no immediate explanation offered for the Serbia star's omission.

There was no hint of any problem on Friday when Vidic attended the official unveiling of David Moyes as United's new manager.

His absence may be connected to the treatment he needs for a chronic knee injury that has ruled him out for virtually 12 months and a fresh problem would be a major concern for Moyes ahead of his first season in charge at Old Trafford after succeeding Alex Ferguson.

As anticipated, Dutch striker Robin van Persie and Spanish goalkeeper David de Gea will both miss Saturday's opener against a Singha All Star XI in Bangkok after being given additional time off following their international commitments, although they are due to join up with Moyes' men in Sydney.

Japanese midfielder Shinji Kagawa will also be a late arrival, linking up with his team-mates in Japan on July 21 after a rest following his country's Confederations Cup campaign.

Javier Hernandez, rested after international duty, Chris Smalling (foot), Ashley Young (ankle) and Nani (broken nose) were also missing from the tour party.

Earlier, Moyes confirmed that new signing Wilfried Zaha will join Manchester United's squad for their pre-season tour of east Asia and Australia.

Zaha only began pre-season training on Monday after taking time off to recover from England's European Under-21 Championship campaign and Moyes wanted to talk to the former Crystal Palace man before deciding whether to take him along on the trip.

"He will travel with us on the tour," Moyes told talkSPORT.

"He has only been with us for two days but I will take him away, see how he goes and have a look.

"This club has a great record of putting young players in the team. Hopefully Wilfried can be one of them."

Wayne Rooney will also be part of the tour, although there has been no further developments on his future, with Moyes again insisting that the 27-year-old striker was not up for sale.

"The club have already stated Wayne is not for sale," Moyes said.

"I have met Wayne two, three, four times. A lot has been said about myself and Wayne over the years but we have a really good relationship. He came to my house, I have been to his recently to have a chat. Also he is here every day.

"I will say he is training great. They are telling me it is the best shape they have seen him in for a long time.

"From that point of view I am taking it as a positive and I am going to try and get the best Wayne Rooney I possibly can."

United's tour takes them to Thailand, Australia, Japan and Hong Kong before a further friendly in Sweden and then Rio Ferdinand's testimonial against Sevilla at Old Trafford on August 9 and the Community Shield against Wigan two days later.