The Eagles will be seeking revenge against Txuri-Urdin after they suffered a slender 1-0 defeat to the Spanish outfit in the reverse fixture two weeks ago.
Match preview
Real Sociedad have seen their four-game unbeaten run in all competitions come to an end after they suffered a narrow 1-0 home defeat to reigning La Liga champions Barcelona last weekend.
Txuri-Urdin were seemingly on course to share the spoils with the Catalan giants until Ronald Araujo headed home a dramatic 92nd-minute winner for the visitors, condemning Imanol Alguacil's side to just their third league defeat of the campaign.
Real Sociedad have dropped eight points in their last four La Liga matches and have subsequently slipped to seventh in the table, six points adrift of fourth-placed Atletico Madrid who have a game in hand.
The Basque-based outfit are faring much better in the Champions League group-stage, though, and are well-placed to qualify for the last 16 for the first time in two decades, as they have accumulated seven points from their first three Group D fixtures and sit level on points with last season's finalists Inter Milan at the summit.
Competing in the Champions League for just the third time in their history, Alguacil's men enter Wednesday's contest having won only five of their last 17 European home games, and success over Benfica would see them record their first Champions League home win since beating Olympiacos 1-0 in their first-ever match in the competition back in September 2003.
Since losing the aforementioned group clash with Real Sociedad a fortnight ago, Benfica have put together a three-game unbeaten run on the domestic front, with a 2-0 Taca da Liga win over Arouca sandwiched between a 1-1 draw with Casa Pisa and a 2-0 victory over Chaves in the Primeira Liga.
Second-half strikes from Fredrik Aursnes and Joao Mario helped the Eagles claim a routine away win against Chaves last weekend, and Roger Schmidt's side remain three points behind league leaders Sporting Lisbon, who they will face in their next top-flight fixture on Saturday.
Benfica are sure to have one eye on that top-of-the-table showdown with Sporting, but they must first turn their attention to their midweek encounter with Real Sociedad as they endeavour to keep their slim hopes of reaching the Champions League knockout rounds alive.
The Portuguese giants are one of just two teams in this season's Champions League, along with AC Milan, who have lost each of their first three group-stage games without scoring, and they are subsequently on the cusp of exiting at the first hurdle for the seventh time in the last 11 years.
Benfica, who have won just two of their last 20 meetings with Spanish opposition, know that anything other than a victory on Wednesday will prevent them from securing a top-two finish in Group D as they currently sit seven points adrift of both Real Sociedad and Inter with three games remaining.
Real Sociedad Champions League form:
D
W
W
Real Sociedad form (all competitions):
L
W
W
D
W
L
Benfica Champions League form:
L
L
L
Benfica form (all competitions):
W
W
L
D
W
W
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Team News
Real Sociedad defender Hamari Traore was forced off with a muscle problem last weekend and is expected to miss out on Wednesday, joining Kieran Tierney (hamstring), Andre Silva (muscle) and Martin Merquelanz (knee) in the treatment room.
The potential absence of Traore will likely see either Aritz Elustondo or Alvaro Odriozola start at right-back, lining up in the back four alongside Igor Zubeldia, Robin Le Normand and Aihen Munoz.
With three goals in as many Champions League group games, including the match-winner in the aforementioned 1-0 win over Benfica, Brais Mendez is set to retain his place in centre-midfield with Mikel Merino and Martin Zubimendi, while a front three of Takefusa Kubo, Mikel Oyarzabal and Ander Barrenetxea should remain intact.
As for Benfica, Juan Bernat is ruled out after missing last weekend's win over Chaves with a muscle injury, while Orkun Kokcu (muscle), Alexander Bah (foot) and David Neres (knee) are also sidelined.
Schmidt may decide to stick with a back three of Antonio Silva, Nicolas Otamendi and Morato, with midfield duo Fredrik Aursnes and Joao Neves potentially continuing in makeshift wing-back roles.
Top scorer Angel di Maria has not netted any of his seven goals across all competitions in the Champions League this season, but the experienced winger is expected to start in attack alongside Rafa Silva and either Arthur Cabral or Petar Musa.
Real Sociedad possible starting lineup:
Remiro; Elustondo, Zubeldia, Le Normand, Munoz; Mendez, Zubimendi, Merino; Kubo, Oyarzabal, Barrenetxea
Benfica possible starting lineup:
Trubin; Silva, Otamendi, Morato; Neves, Mario, Luis, Aursnes; Silva, Cabral, Di Maria
We say: Real Sociedad 2-1 Benfica
There is an element of pressure on both teams to claim maximum points on Wednesday, with Real Sociedad seeking to secure top spot in Group D while Benfica must win to keep their top-two hopes alive.