While the scoreline was only 1-0 to Villa at Villa Park, City were inferior in every metric.
"The results are not good and that's why I have to sleep, look back at the games and figure it out," said Guardiola post-game.
"Rodri is an important player of course but when he is not there we have to find a way to win without him.
"Six points [off the top] and we would prefer to be top of the league but we made three draws and lose today.
"In these years we have found a way to win games but we struggled a bit and we have to find a way.
"It is my job to find a solution. The dynamic changes by winning games. When a team is better you have to recognise it."