Barcelona, Sep 30 (IANS): Spanish clubs FC Barcelona and Valencia each chalked up their first victories of the 2015-16 Champions League campaign with wins over German side Bayer Leverkusen and French team Lyon, respectively.

English club Arsenal lost 2-3 against Olympiakos while fellow English club Chelsea went down 1-2 against Portuguese outfit FC Porto in Tuesday's matches, reports Efe.

Playing without injured striker Lionel Messi, defending champions FC Barcelona had to dig deep after falling behind 0-1 at home as defender Kyriakos Papadopoulos exploited a mistake by goalkeeper Marc-Andre ter Stegen.

Attackers Sergi Roberto and Luis Suarez secured the victory, which left Barcelona at the head of Group E with 4 points, one ahead of Bayer and Belarusian side BATE Borisov, who beat Italian club AS Roma 3-2, also on Tuesday.

Valencia prevailed over Lyon on a great goal by forward Sofiane Feghouli.

Chelsea coach Jose Mourinho's return to Porto, a club he directed to the Champions League title in 2004, was anything but happy, as he watched his current charges underachieve their way to a loss.

Chelsea dropped to third in Group G, with three points. Arsenal, meanwhile, suffered its second embarrassing loss of the campaign.

With no points after two matches, Arsenal are bottom of Group F, led by German champions Bayern Munich with six points. Bayern pounded Croatian Dinamo Zagreb 5-0 on Tuesday.