It’s possible that you’ve seen something like this in one of Tony Jaa’s or JCVD’s movies. However, seeing this move done in actual competition… no way. In a traditional Muay Thai fight between Robby Drought and Mark Frazer, Drought improbably pulled this knockdown kick out of the proverbial hat.
Drought kicked Frazer to the ribs and Frazer caught the kick. He went for a sweep on Drought’s back leg and actually got it. As Drought was falling back, he hit a quick kick to the chops of Frazer. Yes, he actually hit the knockdown blow with the leg that was just kicked out from under him.
It happened so fast that Frazer may have just been stunned because he did not see it coming. Regardless, Drought still managed to stop Frazier shortly after.