Pep Guardiola has labelled Jurgen Klopp's Liverpool team his toughest opponent - saying he's assembled a side even better than Jose Mourinho's Real Madrid.
As a boss of the highest level, Guardiola has come up against the best managers and teams in world football.
He's competed in the game's most prestigious competitions, including the Premier League, La Liga, and Bundesliga, and of course the Champions League.
Guardiola is considered by many to be the world's best coach.
But the great man was unable to guide Manchester City to a third success Premier League title last season, with Klopp's Liverpool storming to the crown.
Paying tribute to Klopp, Guardiola admitted he's the best boss he's ever come up against.
"The toughest opponent I've ever faced in my career is this Liverpool from last year and this one," Guardiola told DAZN.
"If you let yourself be dominated, they lock you in the area and you can't escape. When you dominate them, they run into space like no one else. They are very fast going backwards.
"They are very strong strategically. Their players have great mental strength. [Klopp] is the rival who has made me think about how to beat him the most."
Guardiola added: "I have always said that Real Madrid are a very strong team in my career, they helped me to become a better coach with tough matches and competitions with Jose Mourinho, [Manuel] Pellegrini and all the coaches they had.
"If you ask me which has been the most difficult rival for me to face, it has been Liverpool. The first years when I arrived in England, Liverpool were a bit weaker than now and Real Madrid were stronger. Now, this Liverpool are the hardest I have come across in my coaching career."
* Sign up to the Mirror Football email here for the latest news and transfer gossip
