But after the Gunners had started the match at the Emirates on the front foot, a defensive lapse early on nearly allowed the Greek side to open the scoring.
Within the first 20 minutes, visiting keeper José Pedro Malheiro de Sá sent a goal kick up the field towards striker Youssef El-Arabi.
The Moroccan ghosted past the Arsenal defence’s high line to go through on goal against Gunners’ keeper Bernd Leno.
Though Leno was able to block the shot with his thigh, the fact El-Arabi got the chance to go one-on-one against the German was a warning for the hosts.
And former Arsenal defender Keown criticised their defending, going so far as to cast doubt on their knowledge of the offside rule.
“It was one of those strange situations,” Keown said in his half-time analysis on BT Sport.
“It was from a goal kick, of course there’s no offsides from a goal kick and you wonder there, do the Arsenal back four know because he just ran straight through.
“It’s a fantastic save at the end of it. This sort of position here, what you do from a goal kick is you drop to that sort of position.”
Keown reserved particular criticism for Brazilian defender Luiz, who could be seen appealing for offside.
“As much as I admire playing offside, you’re not going to get an offside from a goal kick so just drop in,” Keown said.
“David Luiz here, he’s got his arm in the air, appealing for offside. You’ve got to get that sorted with the staff and make sure that doesn’t happen.
“That’s a sloppy moment but a great save from the keeper.”