Youssef El Arabi's last-gasp goal in added extra time helped Olympiakos pull off a major upset and oust Arsenal from the Europa League.

El Arabi's strike in the 2-1 win on Thursday at the Emirates secured the Greek side's passage to the competition's last-16 on away goals after Arsenal's 1-0 win in the first leg.

Pierre-Emerick Aubameyang scored a stellar scissor-kick goal in the 113th minute to seemingly put Arsenal through, but El Arabi's game-winner six minutes later left the London club stunned.

Pape Abou Cisse's goal in the second half gave Olympiakos a lifeline to set up the epic ending after the sides went into halftime scoreless.

But the Greek side then came out the break strong, with Cisse getting on the scoreboard in the 53rd minute with a header from Mathieu Valbuena's corner-kick.

Arsenal upped their urgency as the match wore on including solid efforts by Alexandre Lacazette, but the second half concluded without a goal from the hosts.

Until Aubameyang's score, Arsenal controlled possession but couldn't manage to put the ball in the net. Olympiakos forward Georgios Masouras had a great chance when his curling shot from outside the box rattled Bernd Leno's crossbar.

But it wasn't meant to be for English side, as El Arabi found space and directed the ball past Leno from Masouras' deep cross.