Steve Clarke has injury concerns over Shane Long and Chris Brunt, who both missed the 3-0 victory over Sunderland due to knee and groin problems respectively.
Ben Foster, Steven Reid, Matej Vydra and Zoltan Gera all remain long-term absentees, but manager Steve Clarke is likely to keep Stephane Sessegnon in his starting line-up after the midfielder scored on his debut in the comprehensive victory over his former club.
Clarke is likely to replace a large number of the weakened team that featured in the 3-0 victory over Newport County in the previous round, but Saido Berahino is vying to be involved after his hat-trick in that game.
Arsene Wenger admitted he will be forced to shuffle his squad after they claimed their seventh consecutive win against Stoke City at the weekend.
Jack Wilshere will definitely be excluded from the line-up, and Theo Walcott is also unlikely to be risked after pulling out of the Stoke City game with an abdominal muscle problem.
Nicklas Bendtner could make his first appearance of the season, as Arsenal begin yet another chase of their first trophy in eight years.
KICK-OFF: Wednesday, 8.00pm
PAST THREE MEETINGS…
West Brom 1 (Morrison) Arsenal 2 (Rosicky 2), Premier League, April 2013
Arsenal 2 (Arteta 2) West Brom 0, Premier League, December 2012
West Brom 2 (Long, Dorrans) Arsenal 3 (Benayoun, Santos, Koscielny), Premier League, May 2012
Arsenal have beaten West Brom in each of the three meetings between the sides in the League Cup, with all of the games finishing 2-0.
West Brom have only managed one win and one draw in their last eleven encounters against the Gunners.
Aaron Ramsey is currently the top Premier League goal-scorer in all competitions, with 7 goals to his name. He is also the joint highest goal-scoring midfielder in league games this season, level with Yaya Toure.
West Brom to win: 3.7
Arsenal to win: 2.14
TV: Highlights on BBC, Wednesday at 11.05pm