Help! My car rolls backwards when shifting from park to drive.

[MetaGear89]

My car is a mercedes automatic and rear wheel drive. As i'm moving the shifter from park to drive the car rolls backwards gently. My foot is on the brake and I'm on a flat surface but my car still rolls backwards.
My friend said it was doing this because my brakes were worn out. I removed my rear brake pads the other day and found that they were worn badly. If I replace my brake pads and rotors, will this fix my problem? I'm not sure because if it is the brakes because whenever I put the car in park after driving it it remains stationary. If the brakes were that bad, wouldn't I be able to push my car to make it move even if the shifter is in park?

My car rolls backwards as i'm shifting from park to drive

[bmwdirtracer]

Your brakes are not what holds the car while it's in park; that would be the parking pawl of the transmission. While you're shifting to "D", though, you need to push your brake pedal enough to stop the car from moving. If it still rolls with your foot firmly on the brake, you have a brake problem, perhaps air in the lines, if the pedal is spongy feeling.

[philakamrbean]

added to that, if the car is clicking while rolling backwards, that is the parking pawl looking for any place to lock in, but is struggling. Otherwise, it is normal for an automatic to roll back maybe 1-2 inches, 3 at absolute most when going into park. If you're car is rolling several feet, you have a problem.