what I do is this - it's a bit tricky at start, but once u get the hang of it it's solid defense.
when on your opponents half - use the player u control to apply some kind of pressure - don't get to close, don't use R1, just be about 3' from their player (also look where can they pass - good option is to stand in the directon of their best passing option). but that's not the importnat bit.
as soon as you see they are going to move into your own half - switch to someone who's farther down the pitch, and press [] to send someone on their player. use the player you control to close their passing routes. do not press X - it will move the guy u control towards their player - which u don't want to happen. If their player dribbles past the computer controled defender - u can use the guy u control to take the ball out of their possession. again, press X only when really near to the guy in possession.
and lay of the R1- that's the first thing to do - as if u get to snatch the ball outta the attacker's possession while pressing R1 the ball will bounce 5 yards or so, and that's a gamble - another attacker can get hold of possession, and when the computer cheats - they will get possession in a very convenient place (I.E wide open or something).
good luck