The forward was withdrawn in the 80th minute of Saturday’s 2-0 Premier League win over Everton at Old Trafford and immediately headed to the dressing room for treatment.
Subsequent assessment of the injury suggested that Marcus will be unavailable for a few games, but is expected to be back for the season run-in.
The England international’s absence is a disappointment given his red-hot form this season, with 28 goals in all competitions.
But there will also be relief about the prospect of his return for important games in the final weeks of the season.
In the meantime, Erik ten Hag has expressed confidence in other players to step up while Marcus is out of the team.