France defender Raphael Varane left the pitch in tears during Manchester United's 1-1 draw at Chelsea after suffering a knee injury less than a month before the World Cup in Qatar.
United boss Erik ten Hag said it was too soon to know how bad the injury is.
"We have to wait 24 hours and then we will know what [the injury] is." the Dutchman told BBC Sport.
"I can understand (his reaction), we can all probably understand he will be emotional but he also has to wait, you don't know.
"He's experienced but the medics have to do their job, have to make an assessment, set the right diagnosis and from there on come to the conclusion.