Manchester United legend Wayne Rooney has claimed that his former strike partner Cristiano Ronaldo is capable of playing on at the highest level until he turns the age of 40.
Rooney believes the main reason for Ronaldo's longevity is that he has adapted his playing style in order to extend his career.
36-year-old Ronaldo rejoined the Red Devils last month on a two-year deal after a successful, yet incomplete stint at Juventus.
Rooney, who is currently the manager at Derby County in the Championship was asked about his former striker partner at United.
As reported by Sky Sports, United and England's highest ever goalscorer said, "The last time he played here, he was more of a runner, a great dribbler, with pace and power. Whereas now, he's a goalscorer. I think his game has adapted dramatically."
Rooney then went on to hail Ronaldo's fitness levels and said that will be the reason for his longevity in football.
"His ability is obviously one thing, but then he's also looked after himself massively... he's still in great condition. It wouldn't surprise me if he's playing until he's 40, like Ryan Giggs did, and still scoring goals.
"His team-mates will have to work a little harder. But if it's anything like last time - towards the last two years of playing with him - the team allowed him to do that because he scores you goals, and goals win you games."
Ronaldo is expected to make his second debut for Manchester United when the Red Devils take the field against Newcastle United on Saturday.