If you needed solid proof that Zlatan Ibrahimovic should have his own Marvel franchise after retiring from football, then this could be it.
Doctors operating on the Man United player's knee were so taken aback by the sheer level of fitness that they now want him for further research.
Ibrahimovic had sustained drastic ligament damage last month when United beat Anderlecht 2-1.
The striker's agent Mino Raiola said surgeons over at the University of Pittsburgh School of Medicine were shocked by the 35-year-old's peak condition to such an extent they suggested carrying out more tests on the Swede.
"His knee is so strong that the doctors said they had never seen anything like it," Raiola told Swedish newspaper Expressen.
"He has a knee that it is almost impossible for a football player with a 20-year career to have. It was quite clean, there was no harm in it.
"Zlatan is so strong that the doctor wants him back after his career to research on him. They work on the world's best research institutions for the knees and ligaments.
"They research a lot on the subject and that is why they are better than everyone else, and doctors want back Zlatan to do research on him.
"So after Zlatan's career, we will go back and open him up again to do research on his ligaments."
A few weeks ago, Zlatan posted a message to his followers on Instagram, thanking them for their well wishes.
He wrote: 'First of all, thank you for all the support and love. Its no news I got injured so I will be out of fotball for a while. I will go through this like everything else and come back even stronger.
'So far I played with one leg so it shouldn't be any problem. One thing is for sure, I decide when its time to stop and nothing else. Giving up is not an option. See you soon.'