Reliable defenders might not get the limelight of a midfielder or a striker, but they are just as important to a winning football team.
The world's best football clubs have the world's best defenders - and you'll find some of them on this list, which ranks the best centre-backs and full-backs since the turn of the 21st Century.
This list is entirely subjective, but feel free to leave your thoughts in the comments' section below.
Should someone else be in the top 10? Is the rank order wrong? Have your say!