Having a draw between each other gives Arsenal the first position. Arsenal will be happy that they are in the first position even though it is just only by goal difference. Now I think will be concentrating on the Champions League match against Porto. remember, Arsenal is already behind in this one. this is the second leg and Arsenal is going to go in this one by having one goal disadvantage. But it is definitely hard for Arsenal to concentrate on both competitions at the same time. I think they will end up concentrating a little more on the English Premier League.
Honestly, I'm not sure if Arsenal will stay a long time in the 1st place. They have 2 big matches in the next 2 matches. They will play against Chelsea at home and they will play against Man City away. I think there is a big chance for missing points in the next 2 matches, specifically for the match against Man City away.