Mourinho has overseen a dreadful 2018/19 season so far, with United currently on a run of four straight Premier League games without a win and sitting eighth in the table with close to half the campaign now played. It has brought increasing pressure on the Portuguese.
Mourinho is under contract until 2020 after being handed an extension just 11 months ago. But, according to The Sun, a clause in that deal means it will cost United less to sack him if the club fails to qualify for the Champions League.
The tabloid newspaper claims that the United hierarchy have decided that Pochettino is 'the only contender' who can replace Mourinho at the end of the season and are willing to splash out an astonishing £40m to free the 46-year-old from his long-term contract in north London.
That money would compensate Spurs, who only a new deal with Pochettino until 2023 in May, although the figure does not seem to include whatever sum would be owed to Mourinho.
But while it is pointed out that former the Southampton coach has been 'frustrated' by a lack of recent investment in the Tottenham squad, United may have their work cut out persuading him to move to Old Trafford if sacking Mourinho at the end of this season is a genuine possibility.