Unai Emery has returned to a three-man defence for the first time this season with Rob Holding captaining the Gunners.
Holding, not among the quartet of captains, starts alongside Shkodran Mustafi and Sokratis Papastathopoulos as Arsenal return to a back five for the first time since their 4-1 defeat in the Europa League final.
Kieran Tierney and Ainsley Maitland-Niles are the wing-backs whilst Nicolas Pepe also starts.
Emery expects a tough test against the Portuguese side, who came within two late Nicolas Pepe free-kicks of earning victory at the Emirates Stadium last month.
"It’s not an easy game, no," he said. "We played the first match against them and they showed us their capacity.
"Also, Portuguese teams are very organised, they have good players and every coach from Portugal I know is a very good coach.
"We are thinking, after the first result [in London] that was 3-2, that we know here it will be more difficult [as they will be at home]."
Confirmed Arsenal XI: Martinez; Mustafi, Holding, Sokratis; Maitland-Niles, Ceballos, Willock, Tierney; Pepe, Martinelli, Saka
