Ibrahimovic signed for United this summer as a free-agent following the expiry of his contract at Paris Saint-Germain, where the Sweden forward added a Ligue 1 title to the championships he won in Holland, Italy and Spain.
But Mourinho, who can point to title triumphs in England, Spain, Portugal and Italy, challenged Ibrahimovic to prove that he could follow up those successes in the Premier League.
The manager does not believe that Ibrahimovic is past his best and insists the the 34-year-old is physically and mentally ready to have a major impact for United.
When asked whether Ibrahimovic can still cope with the rigours of the English game. Mourinho said: “Yes, because first of all I know him very well. I always think there’s our age in ID terms, but then there’s our real age. Because, for me, the real age is not the age on your ID. That’s just a date when you were born.
“The real age – the real ID – is your body, your brain, your attitude. And this guy is young, his body is amazing. The way he grew up playing the sports he did before football – especially martial arts – he was prepared in terms of his muscles and the mental point of view in a different way to the traditional football player, his DNA, his motivation.
“Let’s be honest, he’s very rich. He’s made money all his career, he’s won a lot of things. You only come to the most difficult championship in the world if you feel you can do it. If you don’t feel you can do it, you go to America, China, stay in the French League one more season.
“So the guy wanted this one more challenge. When I told him that I had won in England, Spain and Italy and he hadn’t – that he’d done Spain, Italy and France – he thought ‘ah, I want to go. I want to win every one’.
“So his motivation is high. His body is amazing. On Sunday he is going to start a specific programme we have prepared before he joins our group on the Thursday, so he has five days just for him. So I expect he is going to be very good for us.”
Having worked with Ibrahimovic previously at Inter Milan, Mourinho feels the centre-forward can be one of United’s leaders on the pitch, despite being a Premier League novice.
The manager said: “Sometimes people say the team has no leaders, it’s this, it’s that, but what we need is everybody with the same kind of mentality. I like communication and push them to communicate. I give a lot of instruction in training.
“It’s difficult for me to do the same in matches so I need guys on the pitch to read the game, to understand what we want. Zlatan is going to be one of them, and I feel already that we have guys to do the same. I don’t think we’re going to have a problem at that level. We have lots of quality.
“When I see our group in the attacking areas. Zlatan, Rashford, Rooney, (Henrikh) Mkhitaryan, (Juan) Mata, all the wingers we have. I think we have lots of quality in attack to produce good football and score goals.”