The Germany international has sustained a back injury in Borussia Dortmund's Champions League defeat to Napoli but is expected to be fully match fit again in little time
The centre-back was forced to leave the pitch shortly before half-time due to a back problem, with the 46-year-old opting to bring on attacker Pierre-Emerick Aubameyang to take his place.
Though Hummels's match fitness for BVB's Bundesliga match away against Nurnberg is unclear, Klopp is hopeful that the Germany international will make his comeback shortly.
"Mats has received a blow to his back on the sciatic nerve," the BVB coach explained to reporters.
"He still has a lot of pain but I assume, however, that he will be better relatively quickly."
Dortmund sit top of the Bundesliga with 15 points from five games.