Guardiola has won titles in Germany, Spain and England, but he thinks the mantle now belongs to somebody else.
The Catalan told Sky Sports: "I was," before taking a step back to say that he never once thought of himself in such high regard.
"What is the best coach in the world?" he added. "I never felt I am the best, never in my life.
"When I won six titles in a row in Barcelona and won trebles, I never felt that. I won because I had extraordinary players at big clubs.
"There are incredible managers, they don't have these players, they don't have these big clubs. I'm a good manager but not the best.
"Give me a team that is not like Manchester City, I am not going to win."