There is a feature in FIFA that helps in defending. Its call MAN MARKING. It allows gamer to choose from 4 players to auto mark the selected players opponent. With this, gamer has a lot of choice to fully utilize the defending game play.
So who to man mark would be the question rite? Now this depends on the formation your opponent choose.
For example vs 433. The player that should be man mark is the winger. Why? Because 433 rely on the wing to attack. Although it has a lone striker, its very hard for him alone to attack. So the best move is to man mark the winger while manual mark the lone striker. So imagine that CPU is helping you in def by man marking the winger.
Although it seems nice and formidable, must be aware that man marking do have its flaw. When the winger finish running, the def who man mark will leave the winger in an almost offside position. This will allow him to run freely if he gets the correct pass.
There are also some players who dont play man marking. They use ZD instead. But as i said before, there is no definite way in FIFA.
So the man marking rules is simple. Mark the most targeted active player base on formation.
Hopefully this will help you guys to get a lot of clean sheet ^^
Does anyone know where does the term "Clean Sheet" came from? ^^