Irwin won the 1998 Rookie of the Year award in the Cup Series driving the Robert Yates Racing No. 28 car, replacing Ernie Irvan. Irwin started the 1998 season by winning the Automobile Racing Club of America race in Daytona in February in a car owned by Yates. During that season, he had one pole, 1 Top 5, and 4 Top 10 finishes on his way to a disappointing 28th-place finish in the final points standings. In 1999 he had 2 poles, 2 Top 5 and 6 Top 10 finishes and finished 19th-place finish in the final points standings.