Danny Drinkwater, another January transfer window arrival, is ineligible after playing earlier in the competition for Burnley, while striker Wesley (knee), midfielder John McGinn (fractured ankle) and goalkeepers Tom Heaton (knee) and Jed Steer (calf) are all sidelined.
Leicester striker Jamie Vardy is set to return from the hamstring injury which caused him to miss last Saturday's FA Cup win at Brentford.
Foxes boss Brendan Rodgers said on Monday that the 33-year-old former England frontman "will have a part to play" at Villa Park, where the sides will resume battle after a 1-1 draw in the first leg.
Aston Villa provisional squad: Reina, Nyland, Guilbert, Engels, Chester, Konsa, Mings, Taylor, Elmohamady, Luiz, Nakamba, Targett, Grealish, Trezeguet, El Ghazi, Hourihane, Jota, Lansbury, Samatta, Vassilev.
Leicester provisional squad: Schmeichel, Ward, Jakupovic, Chilwell, Justin, Pereira, Evans, Fuchs, Benkovic, Soyuncu, Gray, Praet, Tielemans, Ndidi, Maddison, Albrighton, Barnes, Choudhury, Ndidi, Perez, Vardy, Iheanacho.