Greek champions Olympiakos pulled off an unlikely victory in the Champions League on Tuesday.
Marco Silva's side defeated Arsenal 3-2 at the Emirates Stadium in the second Group F fixture of the campaign, leaving the Gunners stranded at the foot of the table.
Felipe Pardo gave Olympiakos the lead in the 32nd minute when Kostas Fortounis found him on the edge of the area from a corner with the Colombian's effort deflecting off bodies in the box and finding its pay wast David Ospina.
Arsenal gave themselves a lifeline three minutes later, however, when Alexis Sanchez played in Theo Walcott whose first-time angled effort bobbled in off visiting keeper Roberto Jimenez.
It was only five minutes until the Gunners lapsed again when Ospina failed to hold Fortounis' inswinging corner, dropping the ball across the line, before attempting to swap it away in what was a calamitous error from the Colombia number one.
The Greek side made a fine triple save on the hour-mark with Jimenez denying first Alex Oxlade-Chamberlain and then Per Mertesacker before Omar Elabdellaoui cleared Santi Cazorla's attempt off the line with his head.
Arsenal managed to again rally in the 65th minute through Alexis who headed home Walcott's chipped cross but it ended in misery for Arsene Wenger's men when Pardo's powerful effort across goal was turned in by Alfred Finnbogason moments later.
The home side huffed and puffed as they searched for a third equaliser but were unable to breach the Olympiakos defence as the Athens outfit came away with a shock three points to throw their hat in the ring for a surprising qualification to the knockout stage of Europe's elite club competition.
Arsenal will have to quickly regroup and prepare for the daunting task of hosting German champions Bayern Munich on October 20 as Olympiakos get set to travel to Dinamo Zagreb who lost 5-0 in Bavaria having beaten the Gunners 2-1 on opening day.
2015/16 UEFA CHAMPIONS LEAGUE - GROUP F
Arsenal (ENG): 2 (Theo Walcott 35', Alexis Sanchez 65')
Olympiakos (GRE): 3 (Felipe Pardo 32', David Ospina (OG) 40', Alfred Finnbogason 66')
Emirates Stadium, London - 59,428
