Maksim Chmerkovskiy and Kirstie AlleyIt may not have looked like a massive tumble, but Maksim Chmerkovskiy clearly injured something rather painfully toward the beginning of his rumba with Kirstie Alley on 'Dancing with the Stars' this week.

Chmerkovskiy said his "thigh just gave out."

In a number filled with emotional meaning for Alley, it was a shame they got off to such a shaky start.

Even after they recovered their feet, Chmerkovskiy held off a couple of beats as he grimaced in obvious discomfort. But then he regained himself and his partner, and they continued the dance.