Ryan Briscoe sustained neck and head injuries in a dramatic crash on lap 21 of Sunday's Indy 300 at Chicagoland Speedway.
The Australian was taken by helicopter to Christ Hospital near Chicago where he is to spend the night under medical inspection. Briscoe was alert throughout his evacuation by the medical staff at the oval circuit.
Briscoe's car launched in the air after he hit Alex Barron's car. Briscoe's car was thrust into the barriers, and upon impact broke into big flames of fire and smashed into three parts - the rear of the car hitting the fencing, the engine thrown on the track, and the tub itself rolling over to the other side of the track.
The race was red-flagged - the first IndyCar race to be stopped for medical reasons since October 2003 - and Briscoe was evacuated by the medical staff and taken to the medical centre. He was seen waving to the crowd while being carried away on a stretcher.
Barron, who was uninjured in the collision, later said: "I felt a bump from the left rear of my car. Ryan was up over me. He was upside down and there was a lot of fire. It was just a quick thud."