Match ends, Arsenal 0, Olympiakos 1.
Arsenal were given a scare by Olympiakos but had enough from the first leg to beat the Greek side on aggregate and reach the Europa League last eight.
Leading 3-1 from the game in Greece, the Gunners were comfortable throughout the first half in London.
Some nerves began to show after Youssef El-Arabi's shot found the net via a deflection off Gabriel to give the visitors hope of repeating last season's shock - when they knocked the Gunners out of the Europa League in the last 32 by scoring in the final minute of extra time at Emirates Stadium.
However, Olympiakos were unable to build on El-Arabi's goal as Arsenal managed the remainder of the tie adequately to progress, helped by a red card shown to Ousseynou Ba for dissent late on.
They will discover their quarter-final opponents when the draw is made in Switzerland at 12:00 GMT on Friday.
Arsenal disappointing but achieve their objective
Arsenal have developed a habit of making life hard for themselves under Mikel Arteta.
Once again, they were their own worst enemies at Emirates Stadium with a tame and occasionally sloppy second-leg display that offered the incentive to their opponents.
Thankfully for the Gunners, most of the heavy lifting for this win had been done in the first leg in Pireas, where late goals from Gabriel and Mohamed Elneny made amends for some poor defending which allowed the Greek side to briefly regain parity in the tie.
That frailty at the back resurfaced again in London, though, with Dani Ceballos' loose pass allowing the Greek side to set up El-Arabi for his goal.
The Morocco striker could also have scored before then to offer an earlier incentive to the visitors, but Bernd Leno's save made amends for the lax defending that allowed him to get within sight of the target from a long ball.
The poor Gunners defending was allied with a profligacy in attack.
Pepe could have settled the tie for good after beating the onrushing keeper but saw his subsequent finish from an angle deflected just wide by a covering defender.
Pierre-Emerick Aubameyang, recalled after being left out of Sunday's north London derby win over Tottenham for breach of "pre-match protocol", could have had a hat-trick and certainly should have taken at least one of the numerous good chances that came his way.
Arteta has called for his side to demonstrate better game management - and while the Spaniard was visibly angered by some of the choices his side made after the deadlock had been broken, he can take some satisfaction from the fact they were able to draw the sting out of the Greek champions after El-Arabi scored.
The fight had already drained somewhat from Olympiakos, but Ba's dismissal - courtesy of a second yellow for throwing the ball down in disgust following a foul - eradicated it.
It was a far from perfect display but more than enough to ensure that the Gunners remain in the hunt for a European trophy and the sought-after prize of a Champions League place that comes with it.
'Nowhere near the levels we could be'
Arsenal manager Mikel Arteta, speaking to BT Sport: "Really happy to be through. Sometimes we have to be fair with ourselves - we were nowhere near the levels we could be.
"We were unstable with the ball and we gave it away. It's impossible when you give the ball away to have any structure. We created enough chances to win but were nowhere near the levels in which we can perform.
"We can't use any excuses. We had fresh players in the side. We started the game really well but then we had a lack of stability. We need to keep the ball and play some passes together and not just keep giving the ball away in transitions.
"We'll get better. When it comes to decision-making and execution, it's a little bit more difficult.
"We need another win in the Premier League and it's a big chance after the international break to get a run together."
Four quarters out of last five for Arsenal
- Arsenal have made it to the quarter-finals for the fourth time in their last five Europa League/UEFA Cup campaigns (knocked out at Last 32 stage last season), after failing to reach that stage in each of their first five attempts.
- Olympiakos have failed to reach the quarter-finals in any of their 23 Europa League/ UEFA Cup campaigns.
- Arsenal have now conceded in each of their last 11 matches across all competitions - their longest run without a clean sheet since a stretch of 14 matches without a shutout between October - December 2019.
- Arsenal have lost three consecutive home matches against an opponent in European competition for the first time ever.
- Arsenal games have produced seven red cards this season in all competitions (5 for, 2 against), the joint-most of any Premier League side (also seven for Aston Villa).
- Olympiakos forward Youssef El-Arabi became just the fourth player to score in three consecutive matches against Arsenal in major European competition, after Lionel Messi (March 2016), Arjen Robben and Robert Lewandowski (both March 2017).
- 2BellerínSubstituted forChambersat 82'minutes
- 23David Luiz
- 3TierneyBooked at 90mins
- 25ElnenySubstituted forParteyat 57'minutes
- 34XhakaBooked at 86mins
- 8CeballosSubstituted forØdegaardat 57'minutes
- 32Smith RoweSubstituted forMartinelliat 81'minutes
- 17Cédric Soares
- 1Malheiro de Sá
- 24BaBooked at 82mins
- 14AndroutsosSubstituted forRandjelovicat 62'minutes
- 6M'VilaBooked at 72mins
- 45ReabciukSubstituted forLalaat 84'minutes
- 19MasourasSubstituted forTué Na Bangnaat 63'minutes
- 7FortounisSubstituted forBouchalakisat 84'minutes
- 27Tué Na Bangna
- Carlos del Cerro Grande
- Shots on Target
Second Half ends, Arsenal 0, Olympiakos 1.
Kenny Lala (Olympiakos) wins a free kick in the defensive half.
Foul by Gabriel Martinelli (Arsenal).
Corner, Arsenal. Conceded by José Holebas.
Kieran Tierney (Arsenal) is shown the yellow card.
Foul by José Holebas (Olympiakos).
Nicolas Pépé (Arsenal) wins a free kick in the defensive half.
Attempt missed. Pierre-Emerick Aubameyang (Arsenal) right footed shot from the left side of the six yard box is too high following a fast break.
Attempt saved. Pierre-Emerick Aubameyang (Arsenal) left footed shot from the centre of the box is saved in the centre of the goal. Assisted by Gabriel Martinelli.
Granit Xhaka (Arsenal) is shown the yellow card for a bad foul.
Andreas Bouchalakis (Olympiakos) wins a free kick in the attacking half.
Foul by Granit Xhaka (Arsenal).
Mohamed Mady Camara (Olympiakos) wins a free kick in the defensive half.
Foul by Thomas Partey (Arsenal).
Substitution, Olympiakos. Kenny Lala replaces Oleg Reabciuk.
Substitution, Olympiakos. Andreas Bouchalakis replaces Konstantinos Fortounis.
Second yellow card to Ousseynou Ba (Olympiakos).
Ousseynou Ba (Olympiakos) is shown the yellow card for a bad foul.
Foul by Ousseynou Ba (Olympiakos).
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