Robben caught the eye against Borussia Monchengladbach on Sunday, before a collision with Gladbach right-back Tony Jantschke resulted in him hobbling off just 24 minutes in to his comeback from a minor back problem.
It proved to be just the start of Bayern's worries as a Raffael double put them to the sword in a 2-0 defeat at the Allianz Arena.
Bayern still look good for the Bundesliga title, sitting 10 points clear of second-placed Wolfsburg.
But with a two-legged UEFA Champions League quarter-final against Porto to come next month, Pep Guardiola will be desperate for Robben to make a speedy recovery, given his astonishing form this term.
In 20 Bundesliga appearances, the Dutchman has plundered 17 goals, with a further two strikes coming from his seven European outings.
