A deflection and an own goal helped Arsenal beat Celtic 2-0 in Glasgow to leave the Gunners with one foot in the Champions League group stages.
Only Barcelona and Dinamo Moscow, in the previous round, had beaten Celtic in the previous 36 European matches at Parkhead.
But Arsene Wenger's side enjoyed a comfortable victory to leave them in a commanding position ahead of next week's play-off second leg.
The Gunners deservedly took the lead two minutes before the break when William Gallas inadvertently diverted a Cesc Fabregas free-kick past the wrong-footed Artur Boruc.
The visitors doubled their lead and put one foot in the group stages in the 71st minute. Gael Clichy escaped down the left and his low cross was turned into his own net by the unfortunate Gary Caldwell.