Manchester United boss Erik ten Hag explained substituting Raphael Varane during their win against Nottingham Forest.
Varane was changed for Victor Lindelof at halftime.
"He had complaints," revealed the manager. "So we didn't want to risk him. We know we have Harry Maguire and Victor Lindelof, good replacements.
"So we don't take the risk, but what the complaint is and if it is really bad, we don't know.
"We have to wait."