The two teams meet in midweek.
Guardiola said, "They are a joy to watch and analyse. When you see them, you are concerned of the quality.
"I said to the players today that we will have to be at a high standard to compete against them. They have better stats in all departments except maybe the final third but what they create and how few they concede I am a big fan of Graham Potter.
"Everyone plays in their position and the ball comes, the courage to play everywhere. I like a lot what they play and it will be a good test tomorrow after a lot of games for everyone. That is my only concern. "