Alexander Lacazette scored the winning goal a week ago, which gives the Gunners a slender 1-0 lead and a potentially important away goal.
Mikel Arteta’s side are unbeaten in 10 across all competitions after their 3-2 victory against Everton on Sunday.
Olympiacos had a crucial domestic match against reigning Greek champions PAOK at the weekend and triumphed 1-0, while their loss to Arsenal a week ago was their only defeat since late November – against the Gunners’ own domestic rivals, Tottenham.
Here’s our prediction for the second leg and everything else you need to know about the game.
What time is Arsenal vs Olympiacos?
The match kicks off at 8pm GMT at the Emirates Stadium.
How can I watch on TV?
The game will be shown live on TV in the UK, and can be watched on BT Sport 3 – coverage starts at 7.30pm.
Can I stream it online?
Yes, BT Sport subscribers will be able to stream the match online via the video player and BT Sport app.
Arsenal: Leno; Bellerín, Mustafi, David Luiz, Saka; Xhaka, Ceballos; Pepe, Özil, Aubameyang; Lacazette
Arsenal 2-0 Olympiacos. The Gunners are already halfway there and have an important away goal to ease the pressure. They’re in good form and their quality should prove to be too much for the Greeks.