Herrera and Mata are said to be dissatisfied with their ‘confused playing role’ under van Gaal and they fear they could miss out on Spain’s Euro 2016 squad.
The duo will reportedly consider their futures at Man United if van Gaal is still in charge in the summer.
Both players are fan favourites at Old Trafford and it would be a bitter blow to see them leave the club.
Mata has enjoyed a string of starts in the first-team this term but Herrera has found chances harder to come by.
Although he has been injured quite often, it is a source of frustration for United fans as the team look much more dangerous and creative with Herrera on the pitch. Discontent appears to be growing within the United ranks and it is becoming increasingly clear that the squad wants van Gaal to leave.