Mikel Arteta demanded Arsenal cut out their defensive mistakes, despite being thrilled with the overall performance of his team against Olympiacos in the Europa League.

Arsenal took a big stride towards the Europa League quarter-finals as they ran out 3-1 winners in the first leg of their last-16 tie in Athens, thanks to late goals from Gabriel and Mohamed Elneny on Thursday.

Martin Odegaard's stunner – his first goal for Arsenal after joining from Real Madrid on loan – put the Gunners ahead, but a mix up between Bernd Leno and Dani Ceballos, who has now made two errors leading to goals in the Europa League this season (no player has made more), allowed Olympiacos to equalise.

Ceballos' mistake follows on from Granit Xhaka's error against Burnley in the Premier League on Saturday, though manager Arteta insisted there is no issue with Arsenal's system, but rather the timing of their passes out from the back.

"We started the game really well, very dominant, created a lot of chances, we could have scored two or three at least in the first half, but we gave them two chances," he told BT Sport.

"We gave them the goal, trying to play out from the back, but we reacted really well.

"Overall, positive things, really positive performances but we have to stop making the errors that are costing goals, because we cannot sustain that at this level.

"It's not concentration, it's about when you play the ball. It's not about structure, decision making, it's about when you play the ball, it makes a whole difference."

Arteta, though, claimed his team cannot play with any fear.

"It's not about stopping the way we play, because this is us and we get our rewards by identifying when we do it and how we have to do it," he added.

"The worst that we can do is get the structure to play, but then have too much fear to play. That's a bad mistake to do that."

Arsenal were worthy winners – the Gunners had 18 shots, compared to six from Greek hosts Olympiacos, and eight of them were on target, while Arteta's side also enjoyed 61.5 per cent possession.

The Gunners have won eight of their nine Europa League games this season – drawing the other – and are the highest scorers in the competition so far this term (27 goals), but Arteta explained the next step is to put in a complete performance.

"We were really dominant. We showed our personality to come here and dominate the game," he said.

"The next step is to do that for 90 minutes and give absolutely nothing to the opponent – we are not there yet. 

"We have some of the best moments that we've played this season, understanding the spaces, the quality, the rhythm, the way we attacked the spaces. How we linked with each other, it was great. We need to keep doing it and do it for longer periods."

Odegaard was particularly impressive in the number 10 role, crafting a game-high four chances and had four attempts – more than any other player.

"It's a great result, three goals away from home and a win in this competition is always big," the Madrid loanee told BT Sport.

"The way we struck back after the goal we conceded, and the mentality of this team – I'm really pleased with everything.

"It showed the spirit in the team, the way we back each other. We knew we had to get a goal. That's what it's about – being a team. When one player makes a mistake, you have to strike back as a team and that's what we did today."