Gabriel Martinelli gave Arsenal the lead on the hour mark, but Pedro Neto found an equaliser ten minutes later.
Arteta later said, “I am very disappointed but very proud as well with what I have seen from the team again. We did the most difficult one to score the first goal but very disappointed with the way we conceded.
"The standards and our defensive habits were nowhere near. They have quality and if you give them space they are going to punish you.
"But then the team reacted in a way that was fabulous with the desire to win, show initiative, take risks and be so dominant but we didn’t manage to score the (winning) goal.
“They destroy every team that comes here in every way, but I thought we were superb. We were very unlucky. We have dominated one of the best teams in Europe but we don’t get the results. That is what is missing."
On players returning to fitness: "We are still missing a lot and some of the guys out there are not in the best condition and that is all we are asking, that they are fit and available and the physical condition to play at this level and we have not had any of that. It was patch, after patch, after patch - a lot of players starting and not in the condition to finish games, so that is what I am praying for."