Chelsea were humiliated by Roma at the Stadio Olimpico as Stephan El Shaarawy stole the headlines with two goals - while in Group A, Manchester United beat Benfica 2-0.
El Shaarawy's brace dented Chelsea's chances of topping the group as Roma held on to their first-half lead. A rocket in the first minute of the match caught Chelsea off guard - while the second was due to a mistake by Antonio Rudiger, who let a long ball bounce past him.
Roma capped off an impressive win with a third goal, a wonderful strike from outside the box by Diego Perotti. Given the solidarity of Chelsea last season, many will question the numerous errors made both in midfield and defence - with N'Golo Kante a huge miss for the Blues.
Despite Anthony Martial missing an early penalty for Manchester United, Mourinho's side sealed a comfortable win over Benfica. Matic's long-range effort struck the post, bouncing off Benfica goalkeeper Mile Svilar and into the net. The goal summed up Benfica's Champions League campaign thus far - laughable.
Daley Blind rounded off an easy win for the hosts from the spot, as Benfica continue their poor Champions League form. Staying in Group A, CSKA found a win away at Basel as Wernbloom's late goal proved to be decisive.
Back to Group C, Qarabag created a real sense of deja vu, as they managed another draw against Atletico Madrid, this time at the Wanda Metropolitano. A bullet of a header by Miguel Madera opened the scoring, with Qarabag taking a shock lead. Atleti bounced back through a Thomas Partey screamer in the second half - but the 10 men from Azerbaijan held firm as they did in the last meeting.
Sporting took a first-half lead over Juventus in Group D, thanks to Bruno Cesar's smart finish. However, a late goal from Gonzalo Higuain secured a crucial point for the Italians. While Barcelona failed to break down bottom of the group Olympiakos away from home.
Meanwhile in Group B, both PSG and Bayern qualified for the knockout stages. The French giants cruised to a 5-0 victory over Anderlecht, sustaining their lead at the top of the group. A clean sheet and plenty of goals meant it was much of the same at the Parc des Princes.
What was surprising was Kurzawa's hat-trick, having only previously scored twice this season - goals from Verratti and Neymar also helped put the Belgians to bed. Bayern Munich won away at Celtic Park as an early goal from Kingsley Coman was cancelled out by a Callum McGregor equaliser - but Javi Martinez proved to be the hero late on a secure the win over Celtic and their spot in the knockout stages.