This should have been a straight-forward night's work for Arsenal, who scored twice early on through Alex Oxlade-Chamberlain and Andre Santos, and should have built from that.
But beware those bearing gifts to Greeks: generous Arsenal defending gave David Fuster a free header and themselves some worrying moments before they became the only Premier League team to win in the Champions League this week.
Doggedly, at times nervily, Arsenal held on, but the memory remains of them being cut open at times, particularly when the Olympiakos substitute Djamel Abdoun began running at Santos.
It all made uncomfortable viewing for Arsene Wenger, who was concluding his touchline suspension with a seat amongst the VIPs. Sitting next to his chief executive Ivan Gazidis, Wenger almost had bouts of St Vitus' Dance at times.
Arsenal's defence still needs sorting and if it hadn't been for some outstanding goalkeeping by Wojciech Szczesny, Olympiakos could have come away with a point to go with the deserved plaudits bestowed on their wonderful fans, who sang throughout.
Oxlade-Chamberlain fired Arsenal ahead on 18 minutes, taking Alex Song's long pass on his chest before embarking on his run into the visitors' box and into the record books. At the age of 18 and 44 days, he became the youngest Englishman to find the target for Arsenal in the Champions League.
One became two after 20 minutes courtesy of Santos. The visitors hit back seven minutes later through Fuster as the Arsenal defence froze following a short corner, but they could not find an equaliser. (© Daily Telegraph, London)