John O'Shea sees no reason why his Manchester United team-mate Ryan Giggs can not be playing top-level football when he is 40.
Giggs has completed 20 years as part of United's first team and he recently signed a new one-year contract extension at Old Trafford.
The 37-year-old has yet to give an indication as to when he plans to retire and O'Shea feels the Welshman is still capable of performing regularly in the Premier League.
"Without a doubt," said O'Shea when asked if Giggs can play until he is 40. "His physical shape hasn't changed since I've known him and he looks after himself so well.
"Depending on injuries he could easily carry on, although I am sure he just wants to take it one season at a time.
"He is just enjoying it so much at the minute so I can't see why he can't but I'll let him decide on that."
Giggs equalled Sir Bobby Charlton's record of 606 league appearances for United on Tuesday when appearing as a substitute against Chelsea and O'Shea believes only Paolo Maldini can compare to the winger in the modern era.
O'Shea added: "You see how the manager has built squads and Giggsy has been a vital part of every single one of them.
"It's just incredible. Maldini springs to mind with AC Milan but I think Giggsy has even gone past him.
"The speed and the balance he still shows to go past whether it be an old, experienced defender or a new, up-and-coming young strong defender is incredible.
"Every cliche in the book has been used about the man already and I am sure they will be said many times again.
"He is an absolute legend."