After scoring 28 goals in all competitions last season, the Swedish striker suffered a major knee injury at the end of last season and is not expected to recover until the new year.

His injury forced United to go shopping for a striker this summer, and Mourinho landed Romelu Lukaku from Everton for a reported £75 million. But in discussing that deal, Mourinho hinted that he may be expecting Ibrahimovic to be available for United six months from now.

"We spent big money on a striker because, with strikers, you either spend or you don't get," Mourinho told reporters.

"And we spent because of what happened to Zlatan and we can not allow ourselves to be without an important, strong striker for the first six months of the season."

Ibrahimovic is a free agent and could sign a short-term deal at Old Trafford if United deem him fit during the winter transfer window.

He continues to use United's facilities in his recovery, and on Tuesday midfielder Paul Pogba said Ibrahimovic was still an important leader at the club despite being out of contract.

The 35-year-old has been linked to a move to MLS, but the LA Galaxy's imminent signing of Villarreal's Jonathan dos Santos appears to rule them out as a destination for Ibrahimovic in 2018.

Meanwhile, Mourinho also claimed that he had to "beg Real Madrid to let me go" after his third season ended in 2013 with the mutual termination of his six-year contract, ahead of moving to the Premier League to lead Chelsea.

AP Photo/Martin Meissner

But he said he does not expect a similar situation at United, where he has already shown progress in restoring the club's prestige following the disappointing spells of David Moyes and Louis van Gaal.

"The hardest part [of rebuilding United] in my opinion was the period where there was an evolution in football overall, in terms of every other team, not just the typical powerful teams, but all the others," he said. "Their evolution in relation to the changes in football allowed them also to be economically strong.

"At the same time there was an evolution and Man United did not follow that evolution and my work is not just about arriving at a football team and developing the football team to attack, football targets and objectives, it was more than that.

"It was to go into the structure and to try to adapt the structure around the football team to a new dynamic. And that was the same at Real Madrid, a big club with big expectations but a difficult period with the evolution of other teams and the distance between Real Madrid and Barcelona growing bigger and bigger and bigger.

"When I arrived it was not just about developing a football team to try to stop that domination, but to also develop everything around the team and in that respect I can see similarities in terms of the difficulties and similarities in terms of the dimension of my job.

"I think what we did last season, Europa League, League Cup, sixth in the Premier League is what gets into your eyes. But I know that my job was much more than just the success in some competitions and being unsuccessful in the Premier League.

"To be honest, with the club [Real]'s structure, they wanted me to stay, they didn't want me to leave. Everybody in the club, president, CEO, the board, myself, we all felt after the years I was there that the difficult part of the job was done and they wanted me to stay.

"In fact, I almost had to beg to let them let me go. I don't think that at United is going to happen, because I don't want to go.

"Real Madrid, for me, was really something that I wanted to do. It was something I had a chance to do twice before and didn't. And on the third time, I don't think you can say 'no' three times to such a club. I wanted to go and win the title in Spain, but it was not for me to stay. I was not in love with my life there. I wanted to come back to England and in that case, to Chelsea."