Lehmann injured in red-card incident
Lehmann was shown the red card three minutes from time with his team leading 1-0, causing a penalty and allowing the hosts to grab a last-gasp equaliser.
Lehmann, 40, pushed striker Aristide Bance for no apparent reason and injured a ligament in the process, medical checks on Monday showed.
He then ripped off a Mainz fan's glasses in a minor scuffle after the match.
Lehmann, who has apologised to his team mates, would also discuss his behaviour with the club, Stuttgart said.
"The incident of last night will be analysed and discussed internally," said sporting director Horst Heldt.
Lehmann, who has also played for Arsenal, AC Milan and Borussia Dortmund, has had a long and successful career which has been marred by his temperamental behaviour.
From throwing an opponent's shoe behind his goal to ripping off a team mate's headband, Lehmann has long been considered the "enfant terrible" of German football.
He became the first player to be sent off in a European Cup final when he was red-carded in Arsenal's 2-1 loss to Barcelona in the 2006 Champions League final.