Andrei Eshchenko,Jano Ananidze,Denis Glushakov and Alexander Samadov are the players they have left behind.
Pedro Rocha is injured and Luiz Adriano is suspended.
This is their squad for tonight
Goalkeepers - Alexander Maksimenko and Artem Rebrov
Defenders - Salvatore Bokketti, George Jikia, Dmitry Kombarov, Ilya Kutepov, Marko Petkovich and Nikolay Rasskazov
Midfielders - Roman Eremenko, Roman Zobnin, Mikhail Ignatov, Alexander Lomovitsky, Lorenzo Melgarejo, Ivelin Popov, Alexander Tashaev, Artem Timofeev, Fernando and Sofian Hanni
Striker - Zé Luis.
They only have one out and out striker, but Fernando and Hanni will no doubt be both played wide in a forward role,Fernando is the big danger at set peices/free kicks and even though they have left several players at home they have some real good players especially in the midfield area.
I've also checked about squad sizes for Europa league games and according to UEFA your allowed a squad of 18 players for Europa league games,apart from the final where you are allowed upto 25.
Teams contesting the Champions League and Europa League finals, plus the Uefa Super Cup, can name a matchday squad of 23 players instead of the 18 allowed in the rest of the competition.
You might note from the squad i've posted,that Spartak have travelled with a squad of 19 players,one more than UEFA state you are allowed.