Scott Dixon's team-mate Dario Franchitti has undergone surgery after a spectacular high-speed crash during Monday's IndyCar round in Houston.
Franchitti's car was thrown into the air and into the crash fencing following the incident on the final lap, suffering concussion, two spinal fractures and a fracture to his right ankle.
He has since had surgery to temporarily stabilize the ankle.
Franchitti will remain in Houston for a few days before being moved to Indianapolis for further evaluation.
Dixon leads the Championship heading into the final round in california.