sup,
I have had this problem LOADS the last few days - pi*s take isnt it? spoils it.
Anyways, i asked about it, and a guy called DOA on here, really helpfull.
if u on 360 like me, when the message comes up, do not press the A button. Press the xbox button on ure control and look at the guys status (when u press the button, go to friends, and then scroll right to the end - the guy u played will be top of the list). wait until his status changes from the game u was playing (e.g - man u 1 - chelsea 0) to somthing like, navagating menu, or offline or summot.
Then click back to the game and press ok on the message.
I've not managed to try this yet, but im assured that the game knows that he quit, and u are awarded with a 3 - 0.... usefull when ure score is only 4,000 at the moment, and u just beat a 1 million score player 7-1
.
hope this helps