Jose Mourinho revealed striker Zlatan Ibrahimovic will be out for a month after Manchester United drew 0-0 with Southampton.
The Swede went off at half-time in United's Boxing Day clash with Burnley, and although Mourinho did not divulge the nature of his injury, he has revealed the timespan.
"Zlatan one month out," Mourinho told BT Sport when asked about United's striking options in light of the head injury sustained by Romelu Lukaku during Saturday's Old Trafford game against the Saints.
Lukaku was carried off on a stretcher wearing an oxygen mask early on after a clash of heads and United could not break down a stubborn Southampton side in his absence as they slipped to third in the Premier League.
The Belgium striker headed over a glorious chance before he was forced off and the hosts had two penalty appeals for handball turned down by referee Craig Pawson.
Mourinho was frustrated his side were denied a spot-kick.
"I think it is also a frustrating afternoon for Craig because he's a fantastic referee, one of the most promising referees in Europe. I feel bad for him," said Mourinho. "We missed easy chances but there was a clear penalty that wasn't given.
"I'm happy with the players' attitude and the players' desires."