Arsenal were given a scare by Olympiakos but had enough from the first leg to beat the Greek side on aggregate and reach the Europa League last eight.
Some nerves began to show after Youssef El-Arabi's shot found the net via a deflection off Gabriel to give the visitors hope of repeating last season's shock - when they knocked the Gunners out of the Europa League in the last 32 by scoring in the final minute of extra time at Emirates Stadium.
However, Olympiakos were unable to build on El-Arabi's goal as Arsenal managed the remainder of the tie adequately to progress, helped by a red card shown to Ousseynou Ba for dissent late on.