Jockey Your Opponent
When an attacker is running at you, simply hold down the L2/LT button to perform a jockey. This means your defender will angle himself correctly towards the ball, and allows him to get close to the attacker. This should make it more difficult for the attacker to beat your player.
You can hold down R2/RT at the same time to fast jockey, allowing your defender to cover a lot of ground and increase their chances of intercepting a pass. Otherwise, be patient and jockey until the time is right, then release both that and the sprint button to challenge for the ball.