A support layer for supporting an artificial turf assembly, said support layer having an upper side and a lower side, wherein the upper side is configured to support the artificial turf assembly thereon, the support layer comprising a plurality of drainage holes extending from the upper side to the lower side for allowing liquid to flow via the plurality of drainage holes from the upper side to the lower side, and also comprising a plurality of channels at the lower side for allowing liquid to flow through the channels along the lower side, wherein at least one of said plurality of drainage holes debouches into one of the plurality of channels, wherein the drainage holes have a widened entrance portion at the upper side of the support layer, wherein the widened entrance portion is beveled towards the drainage holes at an angle of between 140° and 179° with respect to the upper side.