Zlatan Ibrahimovic scored again as Paris St Germain won 2-0 at Dinamo Zagreb to stay second in Group A.
Porto maintained their 100 per cent record in the Champions League this season after beating Dynamo Kiev 3-2 at home to take control of Group A.
Schalke pulled off a 2-0 win to become the first non-English side to win a European game at Arsenal in nine years.
Kostas Mitroglu scored in stoppage time as Olympiacos condemned Montpellier to a 2-1 defeat at the Stade de la Mosson.
Zenit St Petersburg picked up their first win with a 1-0 victory against Anderlecht courtesy of an Aleksandr Kerzhakov penalty.
AC Milan, seven-times winners of the competition, continued their poor form with a 1-0 loss at Malaga.
Bundesliga champions Borussia Dortmund downed nine-times European Cup winners Real Madrid 2-1 at home.
Premier League champions Manchester City, who failed to get out of the group phase last term, are risking the same ignominious exit this time after losing 3-1 at Ajax.