Reports are rife that the Spaniard is far from happy that United officials have delayed offering him a new contract, and that could result in him quitting Old Trafford in the new year.
Herrera would like to stay with United but the fact there is no new deal on the table means he could weigh up his options in the January window, when there will be no shortage of offers.
A number of clubs throughout Europe, including those in his homeland Spain, are keen to do a deal and United may have to move quickly if they wish to secure his future.
United boss Jose Mourinho, who would also like to keep Herrera, has admitted he does not get involved with contract negotiations, so the pressure could again be on Ed Woodward to get the deal done.
Herrera is out of contract at the end of the season and will be free to agree a pre-contract deal elsewhere if United do not tie him down before then.