The starlet has suffered his second injury setback this month and is doubtful for his new side's next match
The 20-year-old had joined his new side on loan from Borussia Dortmund in the summer after seeing his appearances at Signal Iduna Park restricted by the presence of Shinji Kagawa, Mario Gotze and now Henrikh Mkhitaryan.
Leitner subsequently moved to Stuttgart to gain more first-team experience and had started four of the last five games with die Schwaben, although injury appears to have halted his progress.
"Moritz will train individually with our physiotherapist today and go through a light programme," coach Thomas Schneider revealed to reporters on Saturday.
"We’ll see how things develop over the next couple of days. The important thing is that he has no problems."
Early prognosis points to the highly-rated playmaker suffering a heavy bruise to the left knee, but crucially without ligament damage.
This is the second injury set-back the starlet has suffered this month, after leaving the pitch in Germany Under-21's 4-0 rout of Ireland with a foot injury almost two weeks ago.