Arsenal crashed out of the Europa League as Youssef El-Arabi's late strike in extra-time secured a stunning 2-1 victory for Olympiacos, who progressed to the last 16 courtesy of the away goals rule.
Pierre-Emerick Aubameyang, who remarkably missed a golden chance in the final seconds after El Arabi's winner, had seemed to settle the contest in Arsenal's favour with seven minutes of extra-time remaining with a stunning acrobatic effort.
But Olympiacos, who cancelled out Arsenal's 1-0 lead from the first leg thanks to Pape Abou Cisse's header in the second half, chose to write their own script as El-Arabi bundled in Giorgos Masouras' cross at the Emirates Stadium.
Yet the drama was not finished there – Aubameyang somehow slicing wide of a gaping goal from point-blank range as Olympiacos held onto a famous triumph in a last-16 tie that finished 2-2 on aggregate.
Bukayo Saka teed up Alexandre Lacazette's winner in the first leg and the duo combined for the only moment of quality in a sluggish first half, but the goal was disallowed for offside.
Arsenal's first-leg lead was cancelled out eight minutes into the second half when then unmarked Cisse headed in from Mathieu Valbuena's corner.
With Arsenal reeling, Konstantinos Tsimikas raced through their defence and ploughed a dipping strike at goal – Leno pulling off a fine stop at full stretch, with Shkodran Mustafi then making a brilliant block as extra-time was required.
Masouras curled a wonderful strike against the bar as both teams pressed for a winner yet it looked like Aubameyang had settled it when he thumped in an audacious overhead kick.
Olympiacos, though, had other ideas and hesitation from Bernd Leno and David Luiz allowed El-Arabi to prod beyond Leno.
Arsenal could have been saved in the final seconds, but with half of the goal to aim at, Aubameyang fluffed his lines as the Gunners' European hopes were extinguished in agonising fashion.
What does it mean? No Europe a real possibility for shaky Arsenal
A 3-2 win over Everton on Sunday sent Arsenal up into ninth in the Premier League but the Gunners are four points adrift of fifth-place Manchester United. Though Manchester City's potential European ban may open up the chance of qualification for the Champions League, as things stand Arsenal are now just one of a glut of clubs chasing the European spots and now one alternative route in for next season has been chalked off.
Tsimikas heading for big things
Olympiacos' 23-year-old full-back was impressive in the first leg and took his opportunity to shine once more in London, putting in an eye-catching display going forward as well as making some vital interventions in defence, and the Greek seems destined for a big move sooner rather than later.
Astonishing Aubameyang miss will live long in the memory
If ever there was a case of going from hero to zero, then Aubameyang's performance was the perfect example. In the space of 10 frantic minutes, the forward scored what seemed set to be a sublime winner before shanking what should have been a simple finish wide at the most vital of moments.
Arsenal were due to play Manchester City next, but Pep Guardiola's side are involved in the EFL Cup final against Aston Villa, so Arteta takes his team to Portsmouth in the FA Cup on Monday. Olympiacos go up against Panaitolikos a day earlier.