Boasting a 2-1 lead from the first leg, Capoue was sent off as he was being stretchered off the pitch last Thursday. However, the former Tottenham Hotspur man played the full 90 minutes against Getafe three days later despite his apparent injury.
Ex-Arsenal midfielder Francis Coquelin should therefore partner up with Dani Parejo in the middle of the park, but another midfielder in Vicente Iborra is still sidelined with a knee issue.
Spurs loanee Juan Foyth was withdrawn through injury in the first leg and is a major doubt after missing Sunday's La Liga game with Getafe, so Mario Gaspar should feature on the right as Alfonso Pedraza displaces the fit-again Pervis Estupinan on the left.
Raul Albiol - who notched up his side's second goal in the first leg - will return to the defence alongside Manchester United-linked Pau Torres, meaning that Ramiro Funes Mori is likely to make way.
Manu Trigueros will provide support from the left after taking just five minutes to break the deadlock last week, while Samuel Chukwueze will hope to give Granit Xhaka all sorts of problems on the opposite side.
Gerard Moreno - boasting 26 goals for the season - was named among the substitutes at the weekend with the second leg in mind, and with Paco Alcacer being named in the first XI against Getafe, the veteran Carlos Bacca may be given the nod at the Emirates.
Villarreal possible starting lineup:
Rulli; Gaspar, Albiol, Torres, Pedraza; Chukwueze, Parejo, Coquelin, Trigueros; Moreno, Bacca
> Click here to see how Arsenal could line up for this clash