Despite the focus being placed on winning this competition, Emery was always going to make alterations with a trip to Chelsea to come three days later.
Youri Tielemans is the most notable of the players to come into the team, the midfielder having already spoken of his frustration over a lack of minutes since his arrival from Leicester City.
Calum Chambers starts at right-back ahead of Matty Cash, while Clement Lenglet is included in the centre of the backline alongside Ezri Konsa.
In attack, Leon Bailey and Jhon Duran get the nod over Moussa Diaby and Ollie Watkins, who both feature among the replacements.
Emery has resisted temptation to include any prospects on the substitutes' bench, signalling his intent to make a winning start to the group stages.
The big surprise in the Legia team is the absence of Tomas Pekhart, the former Tottenham Hotspur and Southampton forward dropping out of the starting lineup.
Legia Warsaw: Tobiasz; Pankov, Kapuadi, Ribeiro; Wszolek, Slisz, Elitim, Kun; Josue, Gual, Muci
Subs: Hladun, Kobylak, Burch, Pekhart, Kramer, Dias, Sokolowski, Celhaka, Baku, Rosolek, Jedrzejczyk, Strzalek
Aston Villa: Martinez; Chambers, Konsa, Lenglet, Digne; McGinn, Kamara, Tielemans; Zaniolo, Duran, Bailey
Subs: Olsen, Marschall, Cash, Luiz, Watkins, Torres, Moreno, Diaby, Dendoncker, J.Ramsey