Real Madrid CF began their title defence in ominous style but Club Atlético de Madrid lost at Olympiacos FC while Borussia Dortmund, Juventus and – just – Liverpool FC also won.
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• Holders Real Madrid make a superb start with four first-half goals to beat Basel 5-1
• Atlético fall 3-2 at Olympiacos while 2013 runners-up Dortmund defeat Arsenal 2-0
• Debutants Malmö and Ludogorets suffer creditable losses at Juventus and Liverpool
• Zenit win at Benfica, Galatasaray deny Anderlecht and Monaco return with victory
Follow the match links for reports, reaction and highlights (until 24.00CET on Wednesday).
Olympiacos FC 3-2 Club Atlético de Madrid
• Arthur Masuaku and Ibrahim Afellay scored early against last season's finalists and after Mario Mandžukić pulled one back, Kostas Mitroglou secured the points despite Antoine Griezmann's late strike.
Juventus 2-0 Malmö FF
• Carlos Tévez ended a 14-game wait for a UEFA Champions League goal just before the hour and struck again late on to see off stubborn debutants.
Real Madrid CF 5-1 FC Basel 1893
• The holders started superbly with Marek Suchý's own goal added to by Gareth Bale, Cristiano Ronaldo and James Rodríguez before the break and Karim Benzema late on.
Galatasaray AŞ 1-1 RSC Anderlecht
• Dennis Praet's fine solo effort in the 52nd minute appeared to have clinched a priceless away win but Burak Yılmaz equalised in added time.
Borussia Dortmund 2-0 Arsenal FC
• Ciro Immobile made it 1-0 just before the break and Pierre-Emerick Aubameyang's chip doubled up three minutes into the second half.