Alexis Sanchez admits he has struggled to adapt to life at Manchester United and wanted to skip international duty with Chile to sort out his problems at the club.

Sportsmail revealed on Wednesday that United staff have been so alarmed by Sanchez's loss of form and dark mood since arriving from Arsenal in January that they fear he could be another expensive South American flop like Angel Di Maria.

The Premier League's highest-paid player on £600,000 a week has scored just one goal in 10 United matches and was dropped to the bench for the FA Cup win over Brighton last weekend.

Alexis Sanchez has failed to live up to expectations since joining Manchester United in January

Sanchez has scored just one goal in 10 games following his move from league rivals Arsenal

Manager Jose Mourinho says United will not see the best of Sanchez until next season

Manager Jose Mourinho says United will not see the best of Sanchez until next season, while the player admits that moving in the January transfer window is the reason why he has dropped below his usual standards.

'As I am self-demanding, I expected something better,' he said. 'The change of club was something that was very abrupt. It was the first time I've changed clubs in January but many things have happened in my life that are difficult.'

Sanchez, 29, was speaking in Stockholm where Chile face Sweden in the Friends Arena on Saturday before playing in Denmark on Tuesday. The forward said that he asked new Chile coach Reinaldo Rueda if he could stay in England to address his issues at United but eventually decided to join his national team after a chat with Manchester City and Chile goalkeeper Claudio Bravo.

'I asked the manager for permission to stay in England but, having thought about it, I thought it would be good to be here to start things off on the right foot,' Sanchez said. 'I told Claudio we should all be united.'

United fear Sanchez could be another expensive South American flop like Angel Di Maria

Since joining United in a swap deal with Henrikh Mkhitaryan, Sanchez has under-performed. His only goal was a follow-up from close range after his penalty was saved against Huddersfield at Old Trafford last month.

He has also lost the ball on 247 occasions - a hundred times more than any team-mate since he arrived - while registering roughly half as many shots per game as he did for Arsenal this season.

Sanchez has looked frustrated on the pitch and isolated off it, often eating alone in the canteen at United's Carrington training base where his downcast demeanour in recent weeks has concerned staff who fear he may be having second thoughts over the move.

They have drawn comparisons with Argentine star Di Maria who struggled to settle after a British record £59.7million move from Real Madrid in the summer of 2014. He joined Paris Saint-Germain for £44m a year later.

ALEXIS EATS ALONE IN THE UNITED CANTEEN, BUT HE'S HAPPY TO DINE WITH HIS CHILE CHUMS! Alexis Sanchez has found life tough since signing for Manchester United. He has struggled to shine on the pitch and often eats meals on his own in the canteen at their Carrington training base, as Sportsmail revealed (below). But life was sweeter for Sanchez (above, second right) on Wednesday as he sat down for lunch in Stockholm with his Chile team-mates Eduardo Vargas, Mauricio Isla, and Charles Aranguiz ahead of their clash with Sweden on Saturday. Advertisement

Meanwhile, an appearance by United striker Zlatan Ibrahimovic at the launch of a new betting company has been postponed amid concerns he could be in breach of FA rules.

Ibrahimovic, who has not played since Boxing Day and is set to leave United this summer, was due to be the celebrity face of BetHard in London on Monday but pulled out after fears he might break FA guidelines about involvement with betting - including instructions not to promote or advertise betting on Premier League football.

The FA are looking to clarify the extent of his involvement, while BetHard hope to set a new date.