This is a surprise that sometimes cannot be predicted because after all the favorite does not mean they can win easily as well as Arsenal in the match against Lens.
They excel in everything in terms of attack and their performance is better, it's just that matches like this and Arsenal's defeat are difficult to predict even though this is not impossible for things like this to happen.
To fight Sevilla, the two clubs are currently still at risk because Sevilla sometimes surprises when playing against clubs from the EPL but on the other hand there is another tough match for Sevilla because in domestic competition they will also face Madrid which of course this will also make them tired.
Arsenal are still favorites in this match but of course the same incident as the defeat against Marseille can also still happen.
You are right, when facing Lens it never crossed my mind that Arsenal would be beaten. In the first few minutes Arsenal game was quite promising, but after the second half they couldn't penetrate Lens' defense.
Therefore, it is quite difficult for me to predict whether Arsenal against Sevilla will go well. Sevilla has not performed well recently, but in the UCL their mentality will improve and Arteta troops need to be careful so they don't let their guard down and concede a goal. The slightest gap can be exploited by the opponent. I hope that both Sevilla and Arsenal can entertain us in this match with intense play. At least we will really look forward to the fast rhythm of the game.