Stuttgart were leading 1-0 against Mainz until former Germany keeper Lehmann, 40, pushed striker Aristide Bance for no apparent reason and was sent off. Mainz converted the penalty and equalised, denying Stuttgart their third league win this season.
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 a headband off a team mate, Lehmann has long been considered the "enfant terrible" of German football.
He also 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 .
"The scene with Jens was unnecessary," Stuttgart coach Christian Gross told reporters. "I know the player Lehmann very well but know little about the person Lehmann.
"I will intensively analyse the situation with him. The success of the team is above everything."
Lehmann, who was fined 40,000 euros this week for what the club said were damaging comments about Stuttgart fans, left the stadium without speaking to reporters and had a minor altercation with a fan outside.
The keeper ripped the man's glasses off before returning them a little later.
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