Mourinho: Valencia has a 'December injury'

The full-back was withdrawn in the 66th minute and replaced by Marcos Rojo after sustaining the problem as the Reds went on to win 2-1 at The Hawthorns courtesy of first-half goals from Romelu Lukaku and Jesse Lingard.

It was the seventh successive game that Valencia, who has been wearing the captain’s armband in Michael Carrick’s absence, has started and the boss feels his injury is the result of him playing in a number of matches in a short period of time.

Speaking in his post-match press conference, the boss said: "This is what I call a December injury. It is an injury of accumulation of fatigue. It is a muscular one. Hamstring. Big, small, medium, I don't know."

When asked how long the no.25 might be out for, he added: "Let's wait. I think he is an experienced guy to not let it go to difficult limits. But it is an injury of fatigue. Everyone in the Premier League especially the ones in more accumulation of cups, European cups, they are at risk."

Valencia has now made 24 appearances for United in all competitions this season, scoring twice – in our 4-0 home win over Everton in September and 3-1 victory away at Arsenal at the start of this month.

The Reds face Championship side Bristol City at Ashton Gate in the Carabao Cup quarter-final on Wednesday night before returning to Premier League action away at Leicester City next Saturday, 23 December, as United embark on a busy run of fixtures over the festive period.