Last season’s finalists Atletico Madrid and Premier League club Arsenal fell to opening day defeats as the 2014/15 UEFA Champions League campaign commenced tonight across Europe.

Heading into the match with a hard earned 2-1 win over city rivals Real Madrid in La Liga last weekend, Atletico fell to a 3-2 loss to Greek side Olympiakos in their Champions League Group A match in Athens.

Arthur Masuaku gave the Greeks a 13th minute lead with a long range strike while Dutch midfielder Ibrahim Afellay, on loan from Barcelona, took advantage of a defensive mix up to double Olympiakos’s lead just after the half-hour mark.

Atletico pulled one back through Mario Mandzukic’s header in the 38th minute before the Croatian blew an opportunity to equalise seven minutes into the second half when he let the ball pass him to the Olympiakos goalkeeper, thinking he was offside after being put through on goal.

That moment’s lapse in judgement, followed by Antoine Griezmann’s fierce strike towards the top corner being kept out by the Olympiakos keeper, would eventually be punished in the 73rd minute when Kostas Mitroglu restored Olympiakos’s two-goal lead from close range.

Griezmann pulled one back for Atletico in the 86th minute to set up a tense finale, but Olympiakos held on to claim a win which put the Greek side in second place behind Juventus after the Italian champions opened their campaign with a 2-0 win at home to Mälmo FF courtesy of a Carlos Tevez brace.

Elsewhere in the Champions League tonight, goals either side of half-time from Ciro Immobile and Pierre-Emerick Aubameyang gave Borussia Dortmund a 2-0 win over Arsenal at the Signal Iduna Park.

Dortmund dominated play all through, with Immobile giving the bumblebees the lead on the stroke of half-time, pulling clear of two Arsenal players before slotting past Wojciech Szczesny into the bottom corner.

And the German side made it 2-0 two minutes into the second half when Aubameyang was sent clean through on goal, with the Gabon international fumbling the ball past an onrushing Szczesny before regaining his composure to double Dortmund’s lead.

Aubameyang came close to making it 3-0 but his effort from just outside the area bounced off the Arsenal crossbar as Dortmund settled for a convincing win that put Jürgen Klopp’s side top Group D after matchday 1.

Galatasaray and Anderlecht played out a 1-1 draw in the other Group D match in Istanbul, with Burak Yilmaz earning a share of the spoils for Galatasaray with his stoppage time goal.

And in Group C, Zenit lead following a 2-0 win at 10-man Benfica while Joao Moutinho’s strike was enough to give Monaco a lone goal win at home to Bayer Leverkusen and second place in the group.