A device and methods for intervertebral spinal fusion of adjacent intervertebral bodies. An intervertebral spacer is positioned within a narrow disc space between adjacent intervertebral bodies of a patient. The spacer is arranged with upper and lower guides. The guides are adapted to simultaneously guide the deployment of upper and lower anchors of an anchoring device into their respective intervertebral bodies. The spacer is also adapted to lock the upper and lower anchors to the spacer in the deployed position.