The Telegraph reports that any such understanding has been rejected by the Red Devils and an earlier report by The Manchester Evening News, which stated that a verbal agreement has been concluded between the player and United has been denied. The Blues are close to completing a deal for Monaco midfield stalwart Tiemoué Bakayoko, leading to reports that Matic would be surplus to requirements under manager Antonio Conte.
The Red Devils have also been linked with a move for Eric Dier from Tottenham Hotspur but the England international is believed to be deep in the plans for manager Mauricio Pochettino and is therefore unlikely to be available for transfer.
Mourinho has been heavily pursuing a defensive rock in midfield to partner Pogba, so that the midfielder can finally fulfil his potential, with Monaco midfielder Fabinho and Paris Saint-Germain stalwart Blaise Matuidi also linked with a move.
Matic was an important figure in the Chelsea line-up last season, making 30 starts in the league alongside N'Golo Kante, helping them win the title for the second time in three years. Matic was preferred over Cesc Fabregas, who was brought in late in games to influence the play as a deep-lying playmaker.
The Serbian shares an amicable relationship with Mourinho, given that the Portuguese man brought him back to the Premier League in 2014 and went on to win the title with Chelsea a year later.
United are currently stacked in midfield, with Michael Carrick signing a new contract while Marouane Fellaini and Ander Herrera are also pushing for a place alongside Pogba. The 28-year-old's arrival would have added some much needed defensive stability in midfield, especially with United attempting to challenge on all fronts, having qualified for the Champions League in the coming season.