Mourinho wanted Sanchez to make proper use of this summer to get to grips with what it takes to play for him as well as get in tune physically.
José Mourinho had an array of options to choose from when selecting his new club captain, with many fans hoping Paul Pogba would be awarded the armband after the midfielder displayed his leadership skills in the World Cup for France.
Last season he was awarded the Jimmy Murphy Young Player of the Year award at Old Trafford, recognising the impact he made after coming back from surgery a knee injury.
"Carrick is also helping me in every training session and it is very important".
"Valencia will be the captain", Mourinho is quoted as saying by ManUtd.com.
Alexis Sanchez joins other squad members go through their paces in the California heat
Fellow forward Alexis Sanchez has been given the green light to join up with the squad in the United States.
Man United are still looking for their first Premier League title since Sir Alex Ferguson retired in 2013. "Mexican teams are always intense, they press a lot, they are quick and they showed that today".
He added: 'No (Romelu) Lukaku, no (Marcus) Rashford, not here and probably not for the start of the Premier League. "We didn't want to lose him because of that and he's recovering really well and we think he can start training back in England but not ready for the start of the season". When Mata went to the sides, it was a kid that trained with us for the first time this pre-season (Mason Greenwood).
Pep Guardiola led Manchester City to the title last season with his unique brand of free-flowing attacking football.
Sanchez impressed on his comeback after a visa issue delayed his arrival in America but United created few chances and San Jose will feel they did enough to win.
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