In NGA, we have a technique called the "Body Block", which works quite well against this sort of insane attack. If the attacker commits that much forward momentum, the Body Block throws our body at their legs (around knee level) to cut them out from under them. It's surprisingly effective - and effectively surprising - for something that looks like a playground technique.
I've always loved that technique. We even used to use it in tournaments (at feet level rather than knees) No scoring from it, but the look on the other guy's face...priceless.