Olympiakos celebrate their goal
Manchester City missed out on a Europa League place after ending their miserable Champions League campaign with a defeat by Borussia Dortmund, while Arsenal’s poor form continued going down 2-1 at Olympiakos, which meant they finished second in their group.
Ajax's defeat by Real Madrid meant City would have finished third in Group D had they beaten the German champions.
But Dortmund posed the greater threat, forcing a series of saves from Joe Hart before Julian Schieber slid in to score from Jakub Blaszczykowski's cross.
City crash out of Europe without a win in any of their six group games.
And in Greece, Arsenal's poor run of form continued as they wasted the chance to finish top of Champions League Group B with defeat by Olympiakos in Athens.
A Gunners side featuring seven changes started well and Tomas Rosicky slotted them ahead shortly before half-time.
But Olympiakos equalised through a close-range finish by Giannis Maniatis and took a deserved lead thanks to Kostas Mitroglou's curling strike.
Arsenal had already qualified for the last 16 but came second in the pool.
That means they could face the likes Barcelona, Paris Saint-Germain and Borussia Dortmund in the last 16.
While they will be pleased to have reached the knockout stage for the 13th consecutive season, the Gunners have now won just three of their last 13 matches in all competitions.
Attention now turns to Saturday's visit of West Brom in the Premier League, where they sit 10th with only 21 points from 15 games.
This was the third time in four years that Arsenal have lost at Olympiakos in their final group game, and the manner of their surrender should concern boss Arsene Wenger.
The Frenchman and his side complained bitterly about the award of a corner that led to the equaliser, but in truth an average Olympiakos team punished Arsenal for another poor defensive shot.
It looked so different early on as the Gunners, away from domestic troubles, played with a relative lack of pressure,
Wenger started the likes of Marouane Chamakh, Francis Coquelin and Sebastien Squillaci, with 20-year-old Jernade Meade given his full debut at left-back and five teenagers named on the substitutes bench.
The changes seemed to give Arsenal the freshness they needed and their 4-3-3 formation posed a constant attacking threat.
Gervinho, Chamakh and Alex Oxlade-Chamberlain all had early chances before Aaron Ramsey miscued from a fine position.
In other matches, Zenit stunned Milan in Italy 1-0, Malaga drew 2-2 with Anderlecht, Montpellier also drew 1 - 1 with Schalke 04 and Paris SG beat Porto 2 – 1.
UEFA LEAGUE RESULTS
Borussia Dortmund 1 - 0 Man City
Olympiakos 2 - 1 Arsenal
AC Milan 0 - 1 Zenit St P'sbg
Din Zagreb 1 - 1 Dynamo Kiev
Malaga 2 - 2 Anderlecht
Montpellier 1 - 1 Schalke 04
Paris SG 2 - 1 FC Porto