This saying is used for situation in which where two people are fighting over something, a third party takes advantage of it and takes it all. Does it sound idiomatic to English ears? Would it roll off your tongue in the following context? Mary found a sweet and was ready to eat it when Danny got to her and tried to snatch it out of her hands. The sweet dropped on the floor and while Mary and Danny were quarrelling, Johnny quickly retrieved it and popped it in his mouth. Well, as they say, where two are fighting, the third wins. Are there any other expressions that convey the same idea?