Losing Paul Pogba for free was one of Manchester United's worst transfer mistakes in recent times and the beneficiaries Juventus could make their move on another United youngster any day now.
In a rare misjudgement, Sir Alex Ferguson chose to allow French midfielder Pogba to leave as a free agent rather than offer him a new deal in July 2012.
The decision now looks costly as Pogba has been inspirational at Juventus and is valued at around £40m with Real Madrid, Barcelona, Chelsea and Manchester City all allegedly seeking his signature.
The 21-year-old made his debut for Man United in 2011 but doesn't appear to have a first-team future and is currently on loan at Queens Park Rangers.
Keane will be out of contract in the summer and he has been reluctant to put pen to paper on a new deal with suggestions that he is holding out to see if Juventus make contact.
Keane played in the same United youth team as Pogba but suffered a cruciate injury, although he is back to full fitness now.
Juventus' interest will be a warning sign to Man United who must still be hurting from the way they lost Pogba, but the Old Lady could move sooner rather than later.