Mikel, 29, has not played under new Stamford Bridge manager Antonio Conte and there are no plans to renew his contract which runs out this season.
Now the Manchester United boss is ready to take advantage with a cut-price New Year offer for the player the Red Devils thought they had signed ten years ago.
Mikel had just turned 19 when the Old Trafford outfit announced on their website that they had signed the teenager on a four-year contract from Norwegian club Lyn Oslo.
The £4m transfer was done directly with the player and his club — bypassing his agents and he was even pictured in a United shirt.
But Chelsea angrily claimed they had an agreement with the agents to buy him.
The midfielder is yet to make an appearance for the Blues this season
Things turned nasty when it was reported Mikel started to get threatening phone calls and ended up having to take refuge in a safe hotel with a security guard.
He then went missing from Lyn amid stories he had been kidnapped.
The Nigeria captain had actually travelled to London where he went on Sky Sports TV to claim that he had been pressured into signing for United, something they denied, and he wanted to join the Blues.
The matter was resolved when Chelsea paid United £12m and Lyn £4m.
So it will be the second time Mourinho has signed Mikel, who he believes can play in a defensive midfield role in front of the back four.
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