Malaga and Porto became the first teams to clinch their places in the knockout phase of the Champions League.
Group C leaders Malaga drew 1-1 at AC Milan, while Porto also earned a point at Dynamo Kiev in Group A, as both progressed with two matches remaining.
Real Madrid's late equaliser against Borussia Dortmund in Manchester City's Group D means the German champions must wait to seal qualification.
Olympiakos moved to within a point of Arsenal after beating Montpellier 3-1. Porto's qualification put a smile on the face of the Portuguese side's coach Vitor Pereira
Porto's qualification put a smile on the face of the Portuguese side's coach Vitor Pereira
Defeat for the French side means they have been eliminated, while Dinamo Zagreb are also out following their 4-0 loss at Paris Saint-Germain.
Porto, who won each of their opening three matches, saw their 100% record disappear after a largely uneventful 0-0 draw in Kiev. But more importantly the Portuguese side, who rarely threatened their Ukrainian hosts, earned the point they needed to take them through to the last-16.
The qualification hopes of Kiev, whose 60-year-old coach Oleh Blokhin watched from the stands following a recent health scare, look slim after PSG's comfortable home win against Zagreb.
Goals from Alex, Blaise Matuidi, Jeremy Menez and Guillaume Hoarau moved the big-spending Parisians five points clear of third-placed Kiev and closer to the knockout stage.
Olympiakos scored two late goals to secure victory against Montpellier and keep up the pressure on Arsenal.
The Greek side saw Paulo Machado's early opener cancelled out by Younes Belhanda's 66th-minute penalty for the French visitors.
But quick-fire goals from Leandro Greco and Kostas Mitroglou in the final 10 minutes enabled Olympiakos to move one point behind the second-placed Gunners, who drew 2-2 at leaders Schalke.
Champions League debutants Malaga knew victory against seven-time European champions AC Milan, coupled with defeat for Zenit St Petersburg at previously winless Anderlecht, would clinch their qualification as group winners.
It looked to be heading towards a dream night for the Spaniards as they led through Portuguese midfielder Eliseu's first-half strike at the San Siro.
Alexandre Pato's 73rd-minute header restored parity for Milan, but it was not enough to stop Malaga progressing thanks to Anderlecht's 1-0 win against Russian visitors Zenit.
Dieudonne Mbokani's first-half strike enabled the Belgians to earn their first Champions League home win in nine years.
German champions Borussia Dortmund looked set to join Malaga and Porto in the knockout stage as they led 2-1 against Real Madrid at the Bernabeu with just a minute of normal time remaining.
But Real boss Jose Mourinho, who claimed before the match that Dortmund could go on to win the competition, saw Germany midfielder Mesut Ozil rescue a point with an 89th minute free-kick.
All the other three goals were scored before half-time, with Marco Reus's strike and an Alvaro Arbeloa own goal, either side of Pepe's header, putting Dortmund in command.
Ozil's late leveller kept the Spanish champions five points clear of fourth-placed Manchester City, who could only manage a 2-2 home draw against Ajax.