Herrera will extend his future at Old Trafford in one way or another.
That appears unlikely to happen with Herrera settled at the club and his representatives said to be "relaxed" over the situation.
United made a similar move to tie Marouane Fellaini to the club for another 12 months in January.
And according to the Telegraph's James Ducker, Man United will activate a one-year extension clause on Herrera's existing contract if a long term deal can't be agreed before January, and remain confident of providing a satisfatory package for Fellaini, who has emerged as a vital player for Mourinho in 2017.
His contract at Old Trafford expires at the end of the season and the 28-year-old is determined to stay, regardless of losing his first-team place.
The versatile Spaniard has been a hugely important player for Mourinho and has been utilised in a variety of roles to help Manchester United win the Europa League last season and begin challenging for the Premier League title in this campaign. It's another clean sheet and we conceded nearly no chances which is not easy when you come to Portugal.
"We have to play against Benfica at home now and I think, with 12 points, we will be qualified which is very important", he added.
United returned from Portugal with doubts over Marcus Rashford's fitness for Saturday's trip to Huddersfield. He had to run back to the goal, that's why the ball went inside [the line].