The Bayern Munich sporting director is a keen admirer of the 22-year-old's ability but has warned the Spaniard about his attitude
The Spanish midfielder moved to the Allianz Arena from Barcelona last summer and suffered an injury-hit start to his Bundesliga career, limiting him to only six league appearances.
And Sammer feels that the 22-year-old's attitude can get on Guardiola's nerves sometimes, but remains an admirer of his abilities.
"Thiago can be a little lax which drives Guardiola up the wall," the former Germany star told Kicker.
"He has great movement and creativity in his game. He's a fantastic footballer who has a good effect on the field but also off it, which is very good for the club."
Thiago scored his first, and only, goal for the club in the Club World Cup final victory over Raja Casablanca.