Guardiola was full of praise for Sarri's work at Napoli when they played City in the group stages of last season's Champions League and backed him to revolutionise the English game at the start of the campaign.
"As a spectator and coach I try to figure out what the manager is trying to do," said Guardiola, ahead of Sunday's visit of Chelsea.
"I see Chelsea and I can understand what they want to do. And after I see them, they do it. Maybe for other people they don't know exactly what they want to do. But they do it.
"And when you see the team, the players that they have, the bench - it is Chelsea my friend."