Nadeau started his rookie season in 1998 with Elliott-Marino Racing driving the No. 13 Ford car, owned by Marino. After sixteen races, and missing one race due to food poisoning, he was released from his contract in July. One week later, he was signed to Melling Racing to drive the No. 9 car. Melling and Nadeau used the second half of the season to develop a consistent program in preparation for the 1999 season. He had no top 10 finishes, seven DNF's, an average finish of 24.2, and had two results in the top 20. Nadeau finished 36th in the Winston Cup points standings for that season and was third in the NASCAR Rookie of the Year Award standings. He entered his first and only race in the Craftsman Truck Series at Phoenix International Speedway finishing twenty-seventh.