Looks like Thompson caught him on the temple or the ear, though Price was asking for it since his didn't have his left up to guard and was throwing somewhat lazy-looking rights. He was begging to be hit going on like that and Thompson hit him. Still, it didn't look like very powerful shot so it doesn't speak well for Price's punch resistance.
I think he wished he had Wlad's chin tonight, because he probably would have won. He has a British chin :!:
Thats the proof his chin is ****, in heavyweight division everyone can get knocked down/out but this punch had nothing behind it, going down from this shot is bad not being able to continue is embarrassing!