ALAMEDA (CBS SF) — Oakland Raiders starting quarterback Derek Carr suffered a transverse process fracture in his back and will be out at least for the next two weeks, head coach Jack Del Rio announced Monday.

Del Rio told reporters returning from such an injury could take “2-6 weeks.” Backup E.J Manuel will start in Carr’s place against the Baltimore Ravens on Sunday.

“There is a real good chance he will miss this week,” Del Rio said. “With these injuries the time frame is 2-to-6 (weeks)…He said he was sorry. He’s a great kid. He’ll bounce back.”

Carr left the Raiders’ game at Denver late in the third quarter after being shaken up on a sack. He was hit by defensive end Shelby Harris and was going down when defensive end Adam Gotsis flew in and wrapped a padded arm between his helmet and shoulder pads.

The Raiders star remained on the ground for several moments as team trainers and medical personnel came on to the field to tend to him. He eventually was able to get up and walk off the field on his own power, holding his lower back.

It was originally announced he was suffering from spasms, but further examination Monday revealed the fracture.

The transverse process is a bony protrusion from the back of a vertebrae bone in the spine. A fracture results from a sudden extreme twisting or side bending movement.

Carr was leading the Raiders to a playoff appearance last season when he suffered a season-ending broken fibula in a 33–25 Raiders win over the Colts in week 15 of the regular season. Without Carr, the Raiders lost their opening round playoff game.