The Red Devils finished in second place in the Premier League table last season to secure their best finish since 2012-13.
Manchester United, though, ended the campaign without any silverware to heap pressure on Mourinho and his players.
Mourinho was appointed as Louis van Gaal’s successor at the end of the 2015-16 Premier League season.
While the Portuguese head coach has guaranteed Champions League football in successive campaigns, the Red Devils have been title contenders.
Mourinho has been left frustrated following a difficult summer transfer window where Manchester United signed just three players.
The 55-year-old has a history of leaving his employers during his third season in charge, having done so at Inter Milan and Chelsea FC.
Former West Ham goalkeeper Hislop believes Red Devils manager Mourinho will finish his third season at Old Trafford.
“He just signed a new deal in January,” Hislop told ESPN FC. “He becomes too expensive.
“Man United have invested too much in Mourinho to sever those ties in the middle of the season.”
The Red Devils have signed Shakhtar Dontesk star Fred, FC Porto defender Diogo Dalot and Stoke goalkeeper Lee Grant.
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