Luke Shaw will be allowed to leave Manchester United on a permanent basis for around £20m as early as the January transfer window.

The 22-year-old's career at Old Trafford is over just three-and-a-half years on from leaving Southampton for the 20-time English champions.

United had previously been open to Shaw, who has not been involved in a single matchday squad in the Premier League this season, leaving on loan in the New Year.

But after activating the option to extend the England full-back's contract by 12 months until 2019 United want to cash in on Shaw, who does not figure in Jose Mourinho's plans for the remainder of the season or beyond, according to The Times.

Saints have been mentioned with an interest in bringing Shaw back to St Mary's following his departure in 2014 but the move rests on whether Ryan Bertrand joins Manchester City as a back-up to the injured Benjamin Mendy.

Shaw's relationship with Mourinho has totally disintegrated and he has little or no contact with the Portuguese coach. The player himself fears his United career is over, but his exit is complicated by his £130,000-a-week wages.

Turkish giants Fenerbahce are keen on signing Shaw on loan and are willing to pay more than 50% of his wages but the player has no interest in the move.

Though Shaw has spiralled down the pecking order at United - he is behind Matteo Darmian, Ashley Young, Daley Blind and Maros Rojo in the left-back position - at eight months short of his 23rd birthday he represents a viable investment.

A January exit would provide Shaw with an outside chance of forcing his way into Gareth Southgate's England squad for next summer's World Cup in Russia. The likes of Bertrand, Danny Rose and Aaron Cresswell have all been preferred to Shaw in recent squads and it might take injury to at least two players to give him a chance.

But having been subject to stinging criticism over his attitude and commitment from Mourinho, Shaw needs to rebuild his reputation away from United before he can think about his international aspirations.

Speaking after first appearance of the season against Burton Albion in the Carabao Cup, Mourinho said: "He has to work. You [media] saw the [Burton] game, you saw the same as I see. He has to work. He has to improve.

"Look, he doesn't play for six months. I am not expecting him to arrive on Wednesday [against Burton] and to be man of the match or to be running up and down for 45 minutes.

"It's just a process. He doesn't play for a long, long time. You have other players in the Premier League that in this moment who are not starting matches and their managers just say 'they're not in the best conditions'."

United have also extended the contracts of Daley Blind, Ashley Young, Juan Mata and Ander Herrera ahead of their deals expiring next June. Marouane Fellaini's future however remains uncertain with talks over an extension having collapsed.

Luke Shaw
Shaw has played just twice this season for United and his days appear to be numbered. Getty Images