The hosts are sitting in 20th position after three rounds of matches, while La Real are one point better off in 17th place.
Match preview
Plzen are yet to taste defeat in Europe this season after following four wins in qualifying with three consecutive draws in the league phase.
After seeing off Kryvbas and Hearts in qualifying, Plzen began the league phase with an entertaining draw against Eintracht Frankfurt, coming from 3-1 down to draw 3-3 in Germany.
They went on to play out a goalless affair with Ludogorets, before they spurned a golden opportunity to claim maximum points in their away clash against PAOK on matchday three.
Milan Havel and Matej Vydra both found the net in the first half to put Plzen in a strong position, only to see PAOK score in the 84th and 93rd minute to ensure the Czech side had to settle for a share of the spoils.
Since returning from their trip to Greece, they have gone on to beat Sparta Prague and Usti nad Labem in the league and cup respectively, before they fell to a narrow 1-0 defeat in Sunday's away clash with Slovacko.
While they may have lost on their travels at the weekend, Plzen have proven to be a strong side on home turf, having won seven and drawn two of their nine competitive home games.
Real Sociedad have experienced a mixed start to their European campaign, having taken four points from their three matches.
La Real kicked off the league phase with a 1-1 away draw against Nice, before they gave up a slender lead to lose 2-1 in their home meeting with Belgium side Anderlecht.
Imanol Alguacil's side managed to give their European campaign some much-needed impetus with a narrow win over Maccabi Tel Aviv on matchday two, with Jon Pacheco and Sergio Gomez finding the net in a 2-1 victory.
La Real followed that result with a 2-0 home defeat against Osasuna, before they returned to winning ways with a 2-0 away victory against Sevilla following a Take Kubo effort and a Mikel Oyarzabal penalty.
As a result of their successful trip to Andalusia, Real Sociedad have now won each of their previous away matches, extending their unbeaten away run to five matches since they lost to Mallorca on September 17.
La Real will be looking to produce another strong defensive display on Thursday, having conceded just three goals in their eight competitive away matches this season.
Viktoria Plzen Europa League form:
W
W
W
D
D
D
Viktoria Plzen form (all competitions):
D
W
W
D
W
L
Real Sociedad Europa League form:
D
L
W
Real Sociedad form (all competitions):
L
D
W
W
L
W
Team News
Plzen boss Miroslav Koubek is expected to be without the injured trio of Lukas Hejda, Jan Sykore and Rafiu Durosinmi.
Sampson Dweh is suspended following his red card against PAOK, while Prince Kwabena Adu is set to serve a one-match ban for an accumulation of yellow cards.
Those two suspensions could present starting opportunities to defender Jan Paluska and forward Daniel Vasulin.
As for the visitors, they are likely to be without Benat Turrientes, Ander Barrenetxea, Arsen Zakharyan, Pablo Marin and Hamari Traore.
Jon Pacheco could be brought into the side to feature in a back four along with Jon Aramburu, Nayef Aguerd and Javi Lopez.
Alguacil could make further changes to freshen up his side, with Sheraldo Becker and Orri Oskarsson both in contention to start against Plzen.
Viktoria Plzen possible starting lineup:
Jedlicka; Paluska, Markovic, Jemelka; Havel, Cerv, Kalvach, Cadu; Sulc; Vydra, Vasulin
Real Sociedad possible starting lineup:
Remiro; Aramburu, Zubeldia, Aguerd, Lopez; Mendez, Zubimendi, Sucic, Gomez; Oskarsson, Becker
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