Alexis Sanchez is entering a key season in his Manchester United career.

After making the decision to move to Old Trafford in January, Sanchez made a poor start to life with the Red Devils and failed to impress during his opening five months.

Two goals and three assists represented a rather mediocre return for 18 appearances in the famous red jersey.

Nevertheless, there's every reason to suggest a full pre-season with the United squad will do him the world of good ahead of his first complete campaign with the club.

And not only that, but Chile's failure to qualify for this summer's World Cup means the winger is well rested and relaxed for the challenge ahead.

Sanchez missing from US tour

However, there has been something of a hitch in Sanchez's preparations for the new season.

United fans were left confused when Sanchez didn't join the rest of the squad on their pre-season tour to the United States.

The team travelled on Monday with games lined up against Club America, San Jose Earthquakes, AC Milan, Liverpool and Real Madrid.

The reason has been revealed

There was no sign of Sanchez, though, and for hours, the only update United fans received was his Instagram post concerning his new haircut.

Nevertheless, BBC journalist Simon Stone cleared up the situation on Monday afternoon.

He revealed on Twitter: "Understand Alexis Sanchez's present absence from @ManUtd tour is due to visa issue. He accepted 16-month suspended jail sentence in Spain in February. Could be granted a waiver but process taking longer than anticipated.

"Re Sanchez. Actual wording is this "An applicant is inadmissible if convicted of a crime involving moral turpitude". As he is going for specific reason and not intending to stay and can afford good lawyers, if anyone is going to get in, it will be AS.

"Cristiano Ronaldo in same situation re suspended sentence. Juventus also due in States next week so they could have similar red tape to overcome."

A complicated situation indeed.

There's still a chance that Sanchez could join up with the squad in the coming days and weeks, but United fans shouldn't get too excited.

While further complications wouldn't exactly derail his pre-season preparations, it would be a huge blow if he missed out on game-time with his still relatively new teammates.

It's also interesting to note that Juventus' new signing - a certain Cristiano Ronaldo - is also in the same situation.

Jose Mourinho and his squad will motor on regardless but, for the moment, there's no Sanchez to join them.

Do you think Sanchez will come good next season? Have your say in the comments section below.