Ferdinand extended his deal last summer to stay at Old Trafford until 2012.
Yet he admitted: "I'll be 34 when this contract runs out and I'd have to be very lucky with injuries and keep in tiptop shape to go beyond that. If I'm still playing in the first team at 34 I'll be delighted."
Although United have made a slow start to the defence of their Premier League title, Ferdinand claims he is not worried.
He said: "Our aim now is to make sure we're within touching distance at Christmas so we can kick on next year and reel in those teams above us."