The Gunners came from behind to beat Leicester City in the Premier League on Monday as they made it seven straight league successes, which has seen them move to within two points of the top of the Premier League table.
Unai Emery's side have also already beaten Vorskla and Qarabag in the Europa League this term, and will be looking to move onto nine points in Group E when they make the trip to Portugal this week.
Here, Sports Mole looks at how the Gunners could line up against the 18-time Portuguese champions in Lisbon.
Out: Laurent Koscielny (Achilles), Carl Jenkinson (ankle), Konstantinos Mavropanos (groin), Petr Cech (hamstring), Sokratis (ankle)
Doubtful: Ainsley Maitland-Niles (fractured leg), Nacho Monreal (hamstring), Sead Kolasinac (knee)
Arsenal boss Emery is expected to make changes from the Leicester clash on Monday night, but the Frenchman still has a number of injury concerns.
Indeed, the likes of Laurent Koscielny, Petr Cech and Sokratis remain on the sidelines, meaning that the same back four that started against Foxes could remain, with Stephan Lichtsteiner featuring at left-back.
Pierre-Emerick Aubameyang came off the bench to score twice against Leicester, but could be saved for the Premier League clash with Crystal Palace on Sunday.
Emile Smith Rowe, who does not turn 19 until the middle of next year, has been involved in both of Arsenal's Europa League matches this term, and the Englishman should play a part.