Sanchez, who was sentenced to 16 months in prison for tax fraud between 2012 and 2014, hasn't been allowed to travel with the Red Devils to the US.
The Dutchman has moved back to Ajax on a four-year contract for a fee of £18million after spending four years with the Old Trafford outfit, making 141 appearances. No person found guilty of fraud can be granted a visa to enter the country as per the USA law.
Sánchez, however, did not play in the tournament as Chile failed to qualify.
Antonio Valencia and Eric Bailly of Manchester United take part in a first team training session as part of their pre-season tour of the U.S. at UCLA on July 17, 2018 in Los Angeles, California.
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United had posted pictures of Sanchez training at their Carrington base last week and further images emerged of him with friends in Cheshire on Sunday.
However, the other notable player to not be flying to the States does have a move away from Manchester United on the cards.
United have signed right back Diogo Dalot, Brazilian midfielder Fred and they are still looking to acquire the services of a new left back.
The Chile global was reported by El Periodico to have originally transferred his image rights to another company named Inversiones Alsan, a society based in Chile of which he also holds a 99% stake.