The Spaniard, who had returned to training just a few days before, pulled up with a hamstring injury when attempting a back-heel to Antonio Valencia.
Mourinho described the injury as “bad” after the game and expressed anger at how he had been declared fully fit by medical staff when problems were still obviously lingering.
And the 55-year-old, speaking ahead of Man United’s clash with Chelsea, revealed that Herrera would be out for some time, adding that Daley Blind, Marcos Rojo and Phil Jones are all still injured as well.
Jose Mourinho says Ander Herrera is out for 'a few weeks'. Nobody else back from injury. #mufc
— Samuel Luckhurst (@samuelluckhurst) February 23, 2018
United’s midfield suddenly feels far less diverse with both Herrera and Marouane Fellaini on the treatment table.
In other words, the onus on Paul Pogba to bring some zeal to the middle is stronger than ever. There is a genuine danger of United entering a kind of inertia if the Frenchman continues to struggle, and with a crucial stage of the season approaching he needs to make a statement against Chelsea.