Cristiano Ronaldo marked his first Champions League appearance for Real Madrid with a brace as the Spanish giants won 5-2 at FC Zurich, but the match was closer than the scoreline suggested.
The £80 million man netted twice from free-kicks, the first a trademark strike and the second comically let in by Zurich goalkeeper Johnny Leoni, but Madrid's defensive failings were again evident.
The Portuguese opened the scoring in the 27th minute of the Group C clash and Madrid were three goals to the good by half-time thanks to further strikes from Raul and Gonzalo Higuain.
However their lead was reduced to one by Xavier Margairaz's penalty and Silvan Aegerter's header.
Ronaldo added a fourth with a free-kick which somehow found the net after a comical attempt to punch clear by Leoni and Guti chipped in a fifth right at the end.
Filippo Inzaghi struck twice to fire AC Milan to a 2-1 victory away to Marseille.
The veteran put his team ahead in the 30th minute before Marseille's top summer signing Gabriel Heinze equalised early in the second half.
However, Inzaghi made sure his team claimed all three points with 15 minutes remaining.
Paul Scholes popped up 13 minutes from time to ensure Manchester United's bid to reach a third successive Champions League final got off on exactly the right note against Besiktas in Istanbul.
Sent off at the weekend at Tottenham, the 34-year-old ghosted into the penalty area unseen to nod home after Hakan Arikan had saved Nani's blistering shot to seal a 1-0 win for the visitors.
Wolfsburg joined United at the top of Group B after they marked their Champions League debut with an assured 3-1 victory over Juande Ramos' CSKA Moscow at the Volkswagen Arena, Grafite the star of the show with a hat-trick.
The German side were in need of a European pick-me-up after three straight defeats in the Bundesliga and received just that as their Brazilian talisman hit the goal trail.
Grafite netted twice in the first half to put them in the driving seat and completed his hat-trick three minutes from time after Alan Dzagoev's effort for the Russians had threatened to spark a CSKA fightback.
In Group D, Nicolas Anelka proved Chelsea can survive and prosper without banned Didier Drogba as the France international earned the Blues a 1-0 win at home to Porto.
Anelka, given the task of filling a lone role in attack in the absence of the suspended Ivory Coast international, struck three minutes after the interval with a neat clipped finish.
Chelsea are in pole position in the group after Atletico Madrid were held to a disappointing goalless draw at home by Apoel Nicosia.
Thomas Muller made it four goals in four days as his double helped Bayern Munich open their Champions League campaign with a 3-0 win at Maccabi Haifa.
Muller, who only turned 20 on Sunday, netted twice in the final five minutes to end Maccabi hopes of a comeback in the Group A clash in Israel.
The Germany Under-21 international justified his inclusion ahead of Mario Gomez as his late brace made the game safe for Bayern just as Maccabi were threatening to cancel out Daniel van Buyten's 64th-minute opener.
Elsewhere in the group Juventus and Bordeaux shared the spoils with a 1-1 draw on a rain-drenched evening at the Stadio Olimpico.
Vincenzo Iaquinta gave the home side the lead in the 63rd minute, but Jaroslav Plasil equalised 15 minutes from time - despite strong appeals for offside - to earn the French champions a point in Turin.