• ‘If people knew the real injury they would be in shock that I was playing’ • Manchester United forward returned to action in win against Newcastle

Zlatan Ibrahimovic has revealed the career threatening injury he sustained in April was more than the “significant knee ligament damage” that Manchester United characterised it as being at the time.

The Swede made his comeback in the 4-1 win against Newcastle United at Old Trafford on Saturday, entering proceedings on 77 minutes as a replacement for Anthony Martial. It was the 36‑year‑old’s first action since sustaining the injury on 20 April playing against Anderlecht in the Europa League.

While the problem was considered grave enough to question whether Ibrahimovic would play again, he stated it was actually more dire than previously known. “If people knew the real injury, they would be in shock that I was even playing. It was more than the knee but I will keep it personal – that’s why I choose not to talk of it,” he said.

“In my recovery I have not rushed anything; I have been out for six and half months. I have been following protocol and my schedule day by day. The only secret has been working hard. Those close to me know what I have been doing. I was working five, six hours a day.

“When it happened I said giving up was not an option. My only focus was on coming back and coming back better. I know it’s my head playing, not my knee; my knee has to follow. With my experience and career I know what I have to do but I feel good. I am very proud of the moment to play again and for everyone around me because I wouldn’t have done it alone. Thanks to the supporters for keeping me motivated, the coach who’s trusted me, the club that believes in me and my family obviously.”

Play Video 1:13 José Mourinho hails the return of Manchester United talisman Paul Pogba – video

Ibrahimovic received a rousing reception. “It was an amazing reaction from fans but I felt it from day one,” he said. “From the first step in the warm-up, with people singing and cheering for you, it’s what keeps you going. This was not a one-man work, it was everyone’s and thanks to them that I am back on field and can play.”

Paul Pogba also made his comeback from a hamstring injury and was instrumental in United’s victory. Rafael Benítez’s side took the led through a 14th-minute Dwight Gayle goal before Pogba took over.

First he created Antony Martial’s 37th-minute equaliser by driving down the right and crossing for the Frenchman to head home. Then, after Chris Smalling put United ahead just before half-time, Pogba scored United’s third on 54 minutes following a smart Marcus Rashford header. Romelu Lukaku broke a personal seven-game drought on 70 minutes for his 17th of the season as José Mourinho’s team kept the gap to the leaders, Manchester City, to eight points.

Of being able to overhaul Pep Guardiola’s side, Ibrahimovic said: “We can chase City. Why is it not a possibility? We are all here because we want to win and we need to because they are first.”

On Pogba he said: “I can talk of what Paul brings – big quality. It was like he hasn’t been injured for a month. He brings such big quality, a different quality, and I bring experience and mine. I try to help the guys as much as possible and do what I can.”

Marcos Rojo, who sustained a serious knee injury in the same game as Ibrahimovic, also returned to the match-day squad. “This week the manager’s been very happy because he has a full team for the first time this season and as a coach you want those opportunities and alternatives to make changes,” Ibrahimovic said. “We just need to pick and choose. He knows what he is doing even when the number of players are limited because he’s a winner and has been winning every season.”

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Ibrahimovic believes United can win the title and the Champions League. “I think there is a possibility for everything. We were early into it [side’s development] last year and won two trophies and we are stronger this season. We believe we can do it. To win and get the trophies.”

Regarding whether he will extend his one-year contract the forward said: “At the moment I am just thankful I can play football again. I don’t know what the future brings but what happens happens. I am at the age where I can choose what I want to do. I don’t sign five- or 10-year deals. I am just happy to be back playing and doing what I am good at.

“José said: ‘Do whatever you want. I trust in you and you know what you have to do.’ So I was not worried. The contract is all paperwork and I do the physical work.”

Ibrahimovic did not sign on for United again until August. “Even if I had a contract or not, I needed to train. The other’s up to the other people,” he said. “I knew I would stay because I wanted to stay. The numbers have never been an issue. I could’ve signed a deal after two months but didn’t because I am honest with myself. I want to stay because I can perform.”