The surgeons that operated on Zlatan Ibrahimovic's injured knee want to bring the Swedish star back for further study, according to his outspoken agent Mino Raiola.
Ibrahimovic has been out of action since he suffered a cruciate knee ligament injury in United's 2-1 Europa League victory over Anderlecht last month.
The 35-year-old underwent surgery at a specialist facility based in Pittsburgh last week.
Raiola told Swedish publication Expressen.se: 'Zlatan has started rehabilitation at the hospital. His knee is so strong that the doctors said they had never seen anything like it.