Mings took a knock to his calf in Sunday's defeat at Liverpool while Grealish was struggling with tight calves, primarily caused by tight strapping, but the pair will be involved on Thursday.
Victor Lindelof is a doubt for Manchester United's trip to Villa Park.
The Sweden international picked up a back complaint during the first half against Bournemouth last weekend, with Eric Bailly brought replacing the centre-back at half-time.
Aston Villa provisional squad: Reina, Nyland, Steer, Guilbert, Konsa, Mings, Taylor, Elmohamady, Luiz, Nakamba, Grealish, McGinn, Trezeguet, El Ghazi, Hourihane, Jota, Lansbury, Samatta, Vassilev, Davis.
Manchester United provisional squad: De Gea, Romero, Grant, Bishop, Dalot, Fosu-Mensah, Wan-Bissaka, Bailly, Lindelof, Mengi, Laird, Maguire, Shaw, Williams, Pogba, Matic, McTominay, Fred, Fernandes, Pereira, Lingard, Garner, Mata, Chong, James, Ighalo, Greenwood, Martial, Rashford.