Arsenal scraped past Watford winning 1-0 at Vicarage Road to propel themselves back into the top four.
Pierre-Emerick Aubameyang scored the only goal of the game as his determination to charge down Ben Foster saw the goalkeeper’s clearance end up in the back of the net.
With Thursday’s second leg tie with Napoli in mind, Unai Emery adjusted his side. Kostas Mavropanos started with just his second outing for the Gunners this season. Meanwhile, Alexandre Lacazette, Mesut Ozil and Maitland-Niles all dropped to the bench.
After 10 minutes played, Arsenal took the lead thanks to Ben Foster’s howler.
And just a minute later, Watford captain Deeney was sent off for throwing his forearm into the face of Arsenal midfielder Lucas Torreira in a late challenge.
Emery’s side were far from convincing battling against 10-man Watford for 80 minutes.
Henrikh Mkhitaryan had at least three opportunities to put the game to bed. Meanwhile, the Hornets almost capitalised on Arsenal’s lacklustre performance, but Andre Gray couldn’t finish after rounding Leno.
The north Londoners held on to rise to fourth with just five games to play.