Vuillemin joined the Yamaha USA factory racing team to compete in the 2000 AMA Motocross Championships. He began the 250cc Supercross season with a fifth place in the opening round, followed by a second place before scoring his first victory at the third round in San Diego when, McGrath experienced mechanical troubles. At the fourth round in Phoenix, Vuillemin came from behind to pass several top competitors including the previously dominant McGrath to score an impressive victory. It marked the first time that a competitor had been able to catch and pass McGrath from behind. He won two more supercross events to finish the season ranked second behind defending champion McGrath.