Manchester United goalkeeper David de Gea was forced to pull out of the starting line-up for Thursday's Europa League match at FC Midtjylland after sustaining an injury in the warm-up.
An announcement over the speaker system at the MCH Arena shortly before kick-off said De Gea would be replaced in the starting line-up by Sergio Romero.
The Red Devils subsequently confirmed via Twitter that an injury - as yet unspecified - had been the reason.
United already had a lengthy injury list, which it emerged on Wednesday captain Wayne Rooney had joined after sustaining a knee problem in Saturday's loss at Sunderland that is set to keep him out for around six weeks.
United made four changes from that game for the last-32 first leg against Midtjylland, with Memphis Depay, Ander Herrera, Paddy McNair and Donald Love - a first-time starter for the Old Trafford club - replacing Rooney, substitute Morgan Schneiderlin, Cameron Borthwick-Jackson (ill) and Matteo Darmian (shoulder).
Including De Gea, boss Louis van Gaal has 13 senior players unavailable.