Especially when using a back three, both centre-backs at the outside can take on different roles. For instance, a left or right centre-back can become an additional playmaker in midfield, when moving forward during the build-up play. Bayern Munichâ€™s David Alaba established that role, as he played as left centre-back in a back three. He travelled through the left half-space and appeared in the number tenâ€™s space. His role has also been called half-space libero.