Rob Kardashian may have been skeptical about doing Dancing with the Stars, but he has nothing to worry about -- his fam is 100 percent behind him!

Kylie Jenner, back in Los Angeles after her Mercedes-Benz Fashion Week debut in NYC, and big sis Khloe Kardashian visited Rob at his DTWS rehearsal Thursday afternoon. The two grabbed lunch with their bro at the food truck that was on the lot and chatted up his DWTS co-stars Cheryl Burke and David Arquette.

Khloe looked like she's been practicing with the dancers herself -- her bod is slimmer than ever! But will she ever join Dancing with the Stars herself? She told X17online, "Never say never, but I don't know."

Both girls looked like they were making the practice space their runway -- Khloe showed up in a red button-down shirt dress, python-print belt and knee-high boots while Kylie looked sweet as can be in a black lace long-sleeve top, pale pink ballerina skirt and sky-high heels.

We hope Rob enjoyed the company!