Nadeau started the 2003 season as the driver of the MB2/MBV Motorsports No. 01 Pontiac Grand Prix, and quickly had a fourth-place finish at Texas. On May 2, 2003, during a practice session at Richmond International Raceway for the Pontiac Excitement 400, Nadeau was leading the practice session when he suddenly swerved to avoid a slowing car, spun in turn one and hit the wall, driver's side first, at high speed. His car then slowly scraped across the wall for 50 feet before sliding to a complete stop. After he hit the wall, Nadeau responded to his crew before falling unconscious. NASCAR red-flagged the track to cut Nadeau out of his car. He was airlifted to a local hospital in critical condition, only given a six percent chance of surviving his injuries. Nadeau suffered complete immobility of the left side of his body, a skull fracture, concussion, a collapsed lung, and several broken ribs. The injuries meant he required a medical ventilator to breathe. Jason Keller raced for him at the Richmond race, Mike Skinner, Mike Wallace, and Boris Said raced the 01 until the fall Martinsville Race, Joe Nemechek raced in the 01 for the remainder of the season and for the next few years as Nadeau's replacement.