Man United's Zlatan Ibrahimovic out for one month - Jose Mourinho

Manchester United boss Jose Mourinho has said Zlatan Ibrahimovic will be out for one month with a "recurrence" of his knee injury.

Ibrahimovic was not included in the squad for United's 0-0 draw at home to Southampton on Saturday and Mourinho told the BBC after the game that the 36-year-old striker, who missed seven months before returning to action in November, is set for another spell on the sidelines.

"It's the same knee, it's the knee with an incredible problem," he said. "A [36]-year-old man -- a lion, like you say he's a real lion -- but not easy and now he's had a little recurrence and one month out."

Romelu Lukaku also suffered a head injury during the game and, asked by BT Sport if that meant he only had Anthony Martial and Marcus Rashford as options at striker, he replied: "Yeah."

United host Derby County in the FA Cup on Friday, and then have 10 days off before hosting Stoke City. The Champions League round of 16 does not begin until Feb. 21 at Sevilla.

Mourinho refused to be drawn on whether he would need to reinforce the United squad in the January transfer window.

"I don't know," he said when asked if he needed to spend next month. "I really don't know, but I'm happy with the players' attitude, with the players' desire, and I have no complaints about my players."

Mourinho was also critical of referee Craig Pawson after the official decided against awarding a penalty when the ball made contact with Saints defender Maya Yoshida's hand.

Asked if the game had been frustrating for him, Mourinho replied: "Yeah, but I think also for Craig, because he's a fantastic referee and one of the most promising young referees in Europe also. Also bad for him."

He added on the BBC: "Of course we played enough to score goals, of course we missed easy chances, but I'm really unhappy with the penalty -- not with Craig's performance overall but with the penalty."

Speaking later at his news conference, he added: "I watch on the touchline and for me it looked very clear, but 50 metres distance, so I give the referee the benefit of the doubt.

"I know my players, so when I see [Juan] Mata hysterical I could understand immediately, no doubt, and then at half-time I watch it and it is a penalty like Rashford's at Leicester was a penalty, like [Ander] Herrera against [Manchester] City.

"It is unlucky, and I told that without any problem, the referees' performances in these matches, [Michael] Oliver against City, [Jon] Moss against Leicester and Pawson today, were good performances, so unlucky decisions for us that punished us."

Even Yoshida admitted he was fortunate not to concede a penalty, saying: "Sometimes we get decisions from the referee and sometimes we get bad luck from them. Today we got good luck."

Ashley Young, meanwhile, could potentially face retrospective action after he appeared to elbow Dusan Tadic in the stomach but Mourinho said he had "not yet" had a chance to view any footage of the incident.

After their third consecutive draw, United dropped into third place in the table behind Chelsea, who won 5-0 on Saturday, and Paul Pogba said they needed to rediscover their form.

"We wanted to win today, but we could only get the draw. We need to get back in the winning mentality, because it will be better for all of us," he told the BBC. "We didn't have the final pass today, and we had a penalty that wasn't given, and if we had that, and scored, it would've changed the game.

"The pressure is coming from behind, but we have to forget about everyone else, and focus on ourselves."