The England international missed the opening-day win over Tottenham and could sit out the rest of August.
Manchester United utility man Phil Jones has been ruled out for at least three weeks with mild thrombosis.
The England international sat out Saturday's 1-0 victory over Tottenham, after which United confirmed he is set for a longer spell on the sidelines.
The club tweeted: "Phil Jones, who was not involved in today's matchday squad, has mild thrombosis and will be out for a minimum of three weeks."
Jones' injury will not only see him miss United's Champions League play-off tie with Club Brugge but he must also be considered doubtful for England's European Championship qualifying double against San Marino and Switzerland at the start of September.