Manchester United star Zlatan Ibrahimovic revealed his knee injury was worse than previously known, saying people would be shocked he returned.
The Swedish striker made his first appearance since April after coming off the bench in his side's 4-1 Premier League thrashing of Newcastle United on Saturday.
Ibrahimovic, 36, said his injury was far worse than previously known, although he preferred to keep the severity a secret.
"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 told UK newspapers.
"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."
Ibrahimovic scored 28 goals in all competitions for United last season before being released, only to sign a new one-year deal.
The veteran may be coming out of contract again, but he is unconcerned about his future.
"At the moment I am just thankful I can run and push it and play football again," Ibrahimovic said.
"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.
"It's fantastic to be playing. Jose [Mourinho, United manager] 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."
|Cipriani ´at peace´ with latest England snub|
|Laporte: Deschamps must have personal reasons for France snub|
|Morata injury not too serious, claims Chelsea boss Sarri|
|Hansen to leave: All Blacks coach returning focus to World Cup defence|
|I want to fight the champion! - Joshua reiterates Wilder in April ambition|
|Gundogan glad to leave Christmas holidays behind|
|I know how it feels and it hurts - Gundogan on Sterling abuse|
|Celtic 1 Red Bull Salzburg 2: Scottish champions through despite defeat|
|Olympiacos 3 AC Milan 1: Rossoneri crash out of Europa League|
|Arsenal 1 Qarabag 0: Lacazette on target as Saka shines|
|Hansen to leave: All Blacks will take time to name replacement|
|Chelsea condemn alleged anti-Semitic chanting from fans|
|Hansen to leave: The best Opta facts from New Zealand coach´s tenure|
|Hansen to leave: Five contenders to be the next All Blacks coach|
|Hansen to leave: Highs and highs of his All Blacks reign|
|Hansen to leave All Blacks after World Cup|
|Rapid Vienna 1 Rangers 0: Late Ljubicic winner sends Gerrard´s men out|
|Beckham continues to miss Giants practice with quad injury|
|Vidi 2 Chelsea 2: Giroud spares Sarri´s side in lacklustre draw|
|Paris Saint-Germain and Marseille fixtures among latest Ligue 1 cancellations|
|Santos turn to ex-Argentina boss Sampaoli|
|Muller could miss Champions League last 16 after Tagliafico kick|
|Home hope Bekker out in front at Alfred Dunhill Championship|
|Van Bommel in touch with Robben over PSV reunion|
|Pinarello chief confident over Team Sky future|
|Stade make Ospreys tickets free in tribute to teenager|
|WRC great Loeb seals Hyundai switch|
|Madrid rumours better than sack talk, says Pochettino|
|Nadal to join Federer at 2019 Laver Cup|
|Prigoda smashes world record, Hosszu dethroned in Hangzhou|
|Former Juve CEO Marotta takes over at Inter|
|Glenn to stand down as FA boss next year|
|Muller apologises to Tagliafico for kick to the head|
|Pereira pleads for more Manchester United chances|
|Griffin hails ´phenomenal´ Lowry after Warriors demolition|
|I´ve played with Zidane and Henry, but Messi is something else – Pires|
|Dragons forward Jack de Belin charged with sexual assault|
|Durant: Raptors are the real deal|
|Cocu bids farewell to Fenerbahce after ´mutual agreement´ is made over October sacking|
|Australia unchanged for historic Perth Test|
|Champions League draw: The possible last-16 ties|
|Southee happy to be back on home soil|
|I wouldn´t swap Dembele for Neymar – Pires|
|Canelo ready to risk heavy weather against Fielding|
|Raptors upstage Warriors, Davis leads Pelicans with 44 points|
|India skipper Kohli excited by green Perth wicket|
|PSG? I haven´t decided my future yet – De Jong|
|Marcelo: Real Madrid don´t have attitude problem|
|India pair Ashwin, Rohit ruled out of second Test|
|Kovac: Ajax-Bayern draw was amazing|
|Sims re-signs with Dragons until 2022|
|Derrius Guice injury update: Redskins RB (knee) has rehab setback, undergoes 3 more procedures|
|Emery: Arsenal could sign defender in January|
|Phillies sign McCutchen to three-year deal|
|O´Neal thinks his Lakers teams could ´easily´ beat Warriors|
|A-League to add two clubs by 2020|
|Curry says he was ´obviously joking´ about moon landing comments|
|Now the beautiful part starts – Ronaldo ready for Champions League knockout stage|
|Bayern have a lot more potential – Lewandowski not satisfied despite top spot|
|Lyon star Fekir shares plaudits for Champions League progression|
|Mourinho not surprised by United´s defeat to Valencia|
|Motivation no issue for Benfica, claims Vitoria|
|Lewandowski finishes Champions League group stage as top scorer|
|Mourinho: We scored two goals and lost 2-1!|
|England have a diamond - Guardiola hails City´s Foden|
|Sterling´s carefree display invites us to love football more than others hate|
|Juventus achieved their objective, despite everything going wrong – Allegri|
|Never say never - Schmidt not ruling out All Blacks role|
|Bologna´s winning start ended in BCL|
|Di Francesco critical of Roma performance|