Recalling the last meeting between the two clubs, Guardiola said: "The last 15-20 minutes were a disaster. We forgot to do what we have to do. After that, it was easy for Arsenal. Hopefully, it is an unbelievable squad, and this season we can make more of a challenge because Mikel is an extraordinary manager.
"They increase the squad in four or five transfer windows, it is an unbelievable squad and unbelievable team. It is one of the toughest opponents you can find right now in Europe. Step by step, window by window, Arsenal is getting better. Last season in Europe, they made an incredible step forward. For me, it is the most solid team; they don't make mistakes, it's an incredibly solid team. They have pace up front. They have set pieces with Nico [Jover], who was here, in every department we know. I know the quality they have."
He added: "We'll see what we have to do and how players are fit, are expected to play a role in deciding the winner, with Arsenal in a good place for one of those, and we try to complete and be a better team than last season, especially in the last 20, 25 minutes."