Sir Alex Ferguson insists he has not set a date for when he will step down as manager of Manchester United.
Ferguson became Manchester United manager in 1986
The 66-year-old told French radio this week that he could retire in 2011.
But Ferguson said: "It's something I've said quite a bit. If your health is good and you are enjoying your job it could be two or three years, who knows?
"I am not going to pigeonhole myself on that one. It could be four years. Who knows, it could be tomorrow. It is impossible to put a time limit on it."
Ferguson, who has won 18 trophies since he took charge at Old Trafford in 1986, originally planned to retire in 2005 but changed his mind.
He has a hunger for the game and he is enjoying it more than ever
Ryan Giggs on Sir Alex Ferguson
That decision was vindicated as he rebuilt his side and United went on to clinch last season's Premier League crown.
United are still in line for the Treble for the first time since 1999 and face Portsmouth in the FA Cup on Saturday.
They are also aiming to retain their league title and have already booked a place in the quarter-finals of the Champions League after beating Lyon this week.
One of Ferguson's stalwarts, Welsh winger Ryan Giggs, 34, is not surprised that Ferguson sees no immediate end to his reign.
Giggs, who was signed by Ferguson as a schoolboy 20 years ago, stated: "I can't see it in the near future. He has a hunger for the game and he is enjoying it more than ever.
"He is enjoying the way the team plays and his desire is there for all to see. It has got to happen at some time but I can't see it in the near future."