He moved up the four wheel drive Pro-4 class in 2001. The series is the premiere division in the short course off-road series. He had three victories in his rookie season. He finished third in the points standings. He became the first driver to win a race in all three divisions in CORR. Greaves won three races and the series championship in 2002. Greaves finished fourth in the 2003 championship. He won four events that year, including the Potawatomi Governor’s Cup which was sponsored by his long-time sponsor Forest County Potawatomi Bingo. Greaves won four races in 2004, including the $100,000 Borg-Warner Cup at Crandon. He finished fifth in the 2004 championship points. Greaves started slow in the 2005, but finished the season by winning seven consecutive races. He won CORR's Precision Gear 2005 Driver of the Year award. Greaves had a big crash at Crandon in September 2006, but he recovered rapidly. He earned eight victories in 2006, won the season championship, and was named driver of the year. He set the record for the most consecutive wins in CORR history when he won seven races. Greaves entered his first Baja 1000 in November 2006.