I've got an even easier way of doing this.
Load up a game with a real person (I used Cristiano Ronaldo) and then sim to the first league game of the season. If you now go into 'Settings' and turn all the opponants stats down (i.e - Shot Accuracy to 0%) and turn your stats up (i.e - Shot Accuracy to 100%) you will find that this achievement is as easy as the Press START achievement from The Simpsons.
Using this method I managed to score 37 goals with Ronaldo in one game along with 10 assists as Real Madrid beat Getafe 51-0. Even if another play in the league plays out of his skin there is no way that they will be able to get a higher ranking than you as you've done so well.
Once the week is over your achievement will unlock. Below is a video using the same method for you to watch. All credit to the video goes to Cinity Gaming.