Maguire, 28, will be absent for Wednesday’s Champions League match against Villarreal.
And is likely to miss England’s World Cup qualifiers against Andorra and Hungary in October.
The defender limped off in United’s Premier League defeat by Aston Villa last Saturday.
“Harry is more or less definitely out. It doesn’t look good,”
“It’s his calf. That might take a few weeks,so let’s see how quickly he recovers.
Of course he was hoping to play against Villarreal.
He missed the last game we played against them [in the Europa League final in May].”
The severity of Maguire‘s injury means he is unlikely to be included when,
Gareth Southgate announces his Three Lions squad on Thursday.