Just another day in Europe's biggest club competition. Here's a recap of all the action from Wednesday:
Chelsea 1-2 FC Basel
Goals in the final 20 minutes from Mohamed Salah and Marco Streller led Basel to a stunning defeat of Chelsea at Stamford Bridge.
Schalke 04 3-0 Steaua Bucuresti
Steaua defended like mad and played well for 67 minutes before things fell apart and Schalke pulled away thanks to goals from Atsuto Uchida and Kevin-Prince Boateng. Julian Draxler wasn't to be denied either and joined in on the fun in the 85th minute adding a third goal for the Germans.
Marseille 1-2 Arsenal
Napoli 2-1 Borussia Dortmund
Atletico Madrid 3-1 Zenit St Petersburg
Atletico Madrid looked a bit nervy after taking a lead thanks to a Miranda goal, but then allowing Zenit back in the match when Hulk equalized in the 58th. Los Colchoneros responded well though when Arda Turan took the lead back just six minutes later and Leo iced the result in the 80th minute.
Austria Vienna 0-1 FC Porto
Lucho González's 55th minute strike was all Porto needed to open their campaign with a road victory over Autria Vienna.
AC Milan 2-0 Celtic
Celtic did their best against a depleted AC Milan side and came within eight minutes of leaving San Siro with a point, but it wasn't to be. Milan's Christian Zapata scored in the 82nd minute and Sully Muntari quickly doubled the lead three minutes later as the Italians took three points from their group stage opener.
Barcelona 4-0 Ajax
Lionel Messi and Barcelona were barely troubled by Ajax in the first meeting between the two legendary clubs.