Two emerging Napoli heroes, Gonzalo Higuain and Lorenzo Insigne, grabbed the goals as the Italian side beat Borussia Dortmund in a game that saw Dortmund's manager Jurgen Klopp and goalkeeper Roman Weidenfeller both see red.
Klopp was incensed at officials for delaying Nevan Subotic's return to the pitch after an injury, with the defender watching from the sidelines as Higuain headed Napoli into an early lead.
Klopp's reaction earned him an early bath.
It would get worse for Klopp, however, as Weidenfeller was sent off shortly before halftime after handling outside the box as Higuain went through on goal.
That seemed to derail Dortmund, but it was not until Insigne stepped up and curled home a beautiful free kick that the points were sealed.
Juan Zuniga bundled in a late own goal to give Dortmund a glimmer of hope, but it did not prevent the Serie A contenders taking all three points.
Said Dortmund's Nuri Sahin, per UEFA.com:
All things considered, it was a deserved defeat. Napoli passed the ball well and we tried everything we could. Every defeat hurts, especially when you know that a win here would have been huge for our campaign.
I don’t think the players can be blamed today, Napoli simply are a quality side and when you are down one man, it is very difficult.