Robben: Guardiola would talk football at 3am
The Spaniard has been in charge at the Allianz Arena since 2013, winning both the Bundesliga and DFB-Pokal, as well as the UEFA Super Cup and FIFA Club World Cup, since his arrival.
And Netherlands international Robben says he has developed a strong bond with the former Barcelona coach.
"We have a very good relationship," he told The Observer. "I like the way he thinks about football and his tactical flexibility means we've played a few systems.
"It's not like we are a 4-4-2 team. We use all kinds of formations with Pep and this means I can play inside or outside, just behind the strikers or even as a striker.
"That’s fantastic because the way he wants to play, with a very dominant style, suits me perfectly.
"And you can discuss anything with him. If it's 3am, Pep would be happy to talk to you about football.
"After Wolfsburg [a 4-1 defeat] you could see on his face how much it hurt him. He hates losing. But every great manager hates losing.
"If [Chelsea boss Jose] Mourinho loses 4-1... he doesn’t sleep well. They are winners. They're so strong and that's why they are so successful.”
And Robben believes his game has come on hugely under Guardiola.
"When I started working with Pep 18 months ago, I noticed how he goes much deeper into football," he added. "His intelligence is obvious. Tactically he's one of the best in the world and, under him, I have made more steps in my development.
"I've come quite a long way these 18 months."