Liverpool missed the chance to cement top spot in Group C after they suffered a shock 2-0 loss to Red Star Belgrade.
The Reds were top of the group heading into the tie and had the chance to extend their lead over Napoli and Paris-Saint Germain.
However, it was Belgrade who started better as Milan Pavkov netted a quick-fire brace to put the hosts 2-0 up before the 30-minute mark.
The Reds were unable to find a way back into the encounter and had to settle for their second defeat of the campaign.
AS Monaco's poor Champions League campaign continued after they were thumped 4-0 by Club Brugge on home soil.
The visitors got off to a superb start as they raced into a three-goal inside 25 minutes, with Hans Vanaken netting a brace while Wesley netted the third.
The Belgian outfit managed to bag a fourth goal in the 85th minute thanks to a strike from Ruud Vormer.
The win sees Club Brugge move up to third spot in Group A, while the Ligue 1 outfit have dropped to the summit.