Guardiola's Manchester City will host the Reds tomorrow in what promises to be one of the biggest games of the season.
Both sides go into the showdown having made an unbeaten start to the new campaign and it is expected to be a blockbusting showdown.
Guardiola is expecting a tough test from a side who thrashed Arsenal 4-0 last time out and he said: "Jurgen (Klopp) is a top, top manager. Liverpool are well organised and amazing with the ball. They have a lot of quality and are so dangerous.
"It should be a great game tomorrow. Jurgen manages good teams with a lot of intensity.
"They will always be challengers. Liverpool are up there with United in having the most titles here and in Europe.
"They haven't won the title for a long time but this season they are one of the contenders for sure."
Guardiola has been dealt a blow with the news captain Vincent Kompany will miss the game with a calf problem picked up while on international duty with Belgium.
He added: "He has a problem with his calf. I don't think he will be available for tomorrow.
"Maybe we need another one (defender), but we have (Eliaquim) Mangala, we have (Nicolas) Otamendi, we have (John) Stones.
"I am sad (for Kompany). I would like him to be fit. He's played for a while without problems but unfortunately we have lost him. We will try to recover him as quickly as possible."
