Noni Madueke put them ahead after nine minutes and the Gunners should have been cruising after Victor Gyokeres added a stylish second before half-time.

But Arsenal seemed to tire after the break and Gabriel twice had to clear headers off the goal-line before David Raya made a stunning save from Oskar Kubiak.

The clean sheet eluded them when Wiktor Nowak converted David Jurasek’s cross in the last minute, and the Gunners were hanging on throughout stoppage time.

A third victory in four matches saw Arsenal climb to third in the table, but Arteta did not like what he saw in the second half.

“Two very different halves,” he told TNT Sports. “The first one, I think we played at a really high level, exceptional at times. The scoreline should have reflected three or four goals.

“We didn’t do it and at half-time I told them it’s a team with a huge spirit. They will keep running, they will keep believing, they will become even more chaotic. And we didn’t control that at all, right from the beginning.

“The second half we were on the back foot, very sloppy. We gave so many balls away, so many bad clearances, we didn’t keep the ball or the structure at all.

“Then you have to suffer because the teams in the Champions League are really good, so there’s a lot to learn.”

Raya admitted Arsenal were caught by surprise by their opponents’ intensity in the second half.

“I think in the first half we played really, really well,” he told TNT Sports. “We dominated the whole game, creating a lot of chances. I think we could have scored a few more goals.

“Then in the second half it was a completely different story, especially from them. I think they went up a gear and we were a little bit surprised.

“They made it very, very difficult for us, which we have to learn from. We know how important away games are and how difficult places like this can be, and a team like this that go man-to-man all over the pitch.

“It’s a lot of things. Maybe they started pressing a little bit higher with a bit more intensity. I think we had too many giveaways, especially in the final third, and they were running back towards our goal.

“So there was a little bit too much box-to-box football and we have to manage those situations better, dominate those actions, keep the ball and go for the third, fourth and fifth goals.

“But we know how difficult it is and, at the end of the day, it’s three points and that’s it.”

Raya has made a habit of pulling off spectacular saves in Europe, and his stretch to push Kubiak’s header onto a post was among his best.

“Yeah, it was really close. It was very similar to the one against Bayern Munich,” he added.

“I’m just trying to do my job in the best way possible to keep clean sheets because it helps you win a lot of games. Hopefully we’ll get more clean sheets next time.

“I haven’t seen it back. I didn’t even know what happened. I know I got a touch, it hit the post and I don’t know where it hit me again.

“It’s one of those things that goes your way and I’m happy for that.”