Atletico Madrid made it two wins from two games in Group A after defeating Club Brugge 3-1 at the Estadio Wanda Metropolitano.
Antoine Griezmann bagged a brace with goals in the 28th an 67th minute, before Koke rounded off the scoring in the 93rd minute.
Arnaut Groeneveld got the only goal for the visitors, who remain winless after two games.
Borussia Dortmund moved top of Group after recording a 3-0 win over AS Monaco.
After a goalless second half, Dortmund put in an impressive second-half display as Jacob Larsen, Paco Alcacer and Marco Reus were on target to secure the win.
Inter Milan maintained their winning start to the campaign with a come-from-behind 2-1 victory over PSV Eindhoven.
Pablo Rosario put the home side ahead after 27 minutes with a superb strike from distance.
However, Inter hit back through Radja Nainggolan on the stroke of halftime before Mauro Icardi secured the winning goal after 66 minutes.
FC Porto calimed their first win over the campaign with a 1-0 victory over Galatasaray thanks to a solitary strike from Moussa Marega.
Porto currently top Group D, level on points with Schalke, while Galatasaray and Lokomotiv Moscow sit in thrid and fourth respectively.