Arsenal boss Mikel Arteta had no complaints after defeat at Champions League opponents Lens.
Gabriel Jesus had put the Gunners ahead only for Adrien Thomasson and the outstanding Elye Wahi to score for the hosts.
Arteta later said: "They are a really good side, exceptional opponent.
"We took the lead and then in one action they managed to score. We had a big chance straight after the break.
"It's true that we didn't generate enough of a threat in the final third, like on many occasions. We didn't attack certain spaces.
"The difference to the PSV game was in the boxes - we missed some big chances and didn't defend well enough for their goals.
"Mistakes happen in football and they will continue to be there somehow but the difference was made in both boxes. You have to put the ball in the back of the net and defend well.
"It was a big night for us. We weren't able to take the result we wanted but we were able to learn."
On Bukayo Saka's injury, he added: "It was an action. It was a backheel and he felt something on this specific action. He was too uncomfortable to continue."
