Victor Boniface scored his first European goal of the season to give Bayer Leverkusen back-to-back wins as Xabi Alonso’s side beat Samuel Chukwueze’s AC Milan 1-0 at the Bay Arena.
The Nigerian international thought he had given the German champions the lead before half-time only to see it ruled out by VAR.
However, he was set up by Jeremie Frimpong for the winner six minutes into the second half.
Milan’s crosstown rivals Inter picked up their first win of the campaign thanks to a 4-0 victory over outmatched Crvena Zvezda at the San Siro, Hakan Çalhanoğlu and veterans Marko Arnautovic and Lautaro Martinez on target.
Meanwhile, Robert Lewandowski pounced early in both halves as Barcelona rebounded from an opening-night defeat to Monaco with a 5-0 demolition of Young Boys.
PSV Eindhoven were another to notch their first point of the season as they drew 1-1 with Sporting Lisbon with Dutch international midfielder Jerdy Schouten getting the opener only for the visitors to level late on.
Stade Brest had never played in the Champions League before this season.
In Tuesday’s early kickoff, the French team routed Salzburg 4-0 away for a second win in as many games, Senegalese forward Abdallah Sima netting twice.
VFB Stuttgart drew 1-1 with Sparta Prague in the other evening contest.