Mikel Arteta saw Arsenal leave Olympiacos in charge of their Europa League tie following a good win – but admitted his side were once again their own worst enemy as a defensive error almost proved costly.

The Gunners will defend a 3-1 lead at the Emirates Stadium next week and were good value for their round of 16 first leg win in Greece.

Martin Odegaard’s first Arsenal goal had them ahead only for another defensive calamity to gift Youssef El-Arabi the equaliser just before the hour.

With a north London derby encounter at home to Tottenham on Sunday, Arteta confirmed all of his substitutions during the game were tactical rather than due to injury.

Arsenal host their neighbours before welcoming Olympiacos to the Emirates Stadium next Thursday, with the Greek side’s head coach Pedro Martins conceding they are now huge underdogs following the late rally.

“The second goal for Arsenal was decisive,” he said.

“Of course, the situation now is not favourable for us, but we will go after our chances in the second leg and fight for the best.”