Mikel Arteta admitted he was "very concerned" by Arsenal's second-half performance against Slavia Prague, despite the fact his side picked up all three points.

The Gunners were cruising at half-time of the Champions League clash, leading 2-0 through goals from Noni Madueke and Viktor Gyokeres.

It could have been an even bigger advantage, too, with Mikel Merino and Eberechi Eze both having good chances to get on the scoresheet themselves.

However, there was then a significant drop-off after the break. Arsenal were sloppy on the ball and there was an air of complacency to how they approached the second period.

Wiktor Nowak scored for Slavia to set up a nervy finish heading into stoppage-time but Arsenal just about held firm.

"Two very different halves," Arteta said. “The first one, we played a really high level. Exceptional at times I would say. The scoreline should reflect three or fouls goals.

"We didn't do it and at half-time I told them. They are a team with a huge spirit that will keep running, keep believing. They will become even more chaotic.

"We didn't control that at all. Right from the beginning of the first 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. A lot to learn."

Slavia registered 17 shots in the match, five more than Arsenal, and there was some chaotic moments at the back for the visitors.

Gabriel was forced into a desperate clearance under his own bar and David Raya produced one sensational save to tip a header onto the post.

For all that was another superb entry into Raya's growing catalogue of world-class saves, Arteta was irritated that it was required.

"He had to show his quality again, much more than we expected," the Arsenal manager said.

"This is great but very concerned about what happened before that, which is something that obviously we have not shown in the past."

Arteta added: "We were extremely far from our standards in everything that we have to do. In every basic, in every concept and in everything that we discussed to avoid the game that we played in the second half.

"Very far from the standards that we expect from each other but we found a way to hold on to a result and win the game."