As Dolohov became frustrated, he also became sloppy, spells going slightly to the left or right of Draco.  Draco tried the Harry Potter favorite,  expelliarmus.  He didn’t expect it to work, until a wand sailed through the air to land in his hand.  Dolohov was shocked, and before he could focus on it, Draco  stupefied  him.  Dolohov’s body collapsed unceremoniously on the floor.