There was more bad news for Manchester United's supporters after a clash of heads involving Romelu Lukaku.

United and Southampton played out an underwhelming draw at Old Trafford on Saturday in which Lukaku wore an oxygen mask as he was stretchered off the field, and Jose Mourinho revealed after the final whistle that Zlatan Ibrahimovic will be out of action for one month

"Zlatan is one month out," Mourinho said. "I don't know about Lukaku. Of course, you miss your striker and your target man. You only have two attacking players on the bench, (Marcus) Rashford and (Anthony) Martial and you lose one of them immediately. I wanted a third change late in the game and I didn't have a third attacking player so that's difficult."

The revelation came one day after Mourinho suggested that neither Lukaku nor Ibrahimovic are fully fit, as the Swedish forward is working his way back from a long-term layoff.

After Lukaku and Wesley Hoedt clashed heads in the eighth minute, play was paused as the Belgian striker received treatment. The product of RSC Anderlecht looked dazed but was conscious as he was eased onto a stretcher, and was replaced by Rashford six minutes later.

United was jeered off the pitch at the final whistle. The result extended the Red Devils' winless run to four games in all competitions.