In 1999, Suzuki signed him to their Grand Prix team. His debut race with Suzuki in Malaysia resulted in a surprise win, defeating the reigning champion, Michael Doohan. He went on to win the second race in Japan, where he again defeated Doohan. This winning streak put him as a strong contender to challenge Doohan for the championship. However, Doohan retired due to injuries suffered in an accident on the third race in Spain. Afterwards, the main challenge for the championship came from Doohan's teammate, Àlex Crivillé. Roberts failed to find consistency during the rest of the season, notching only two more wins and another four podiums. His lead in the championship subsequently was taken over by Crivillé, who later went on to win the title. Roberts would finish a respectable second in the championship.