Mahan, who celebrated his 21st birthday last month, completed three years at Oklahoma State University. He was runner-up in the 2002 U.S. Amateur Championship, which qualified him for the 2003 Masters Tournament, where he tied for 28th place and led the field with a driving distance of 296.0 yards.
A resident of McKinney, Texas, Mahan attracted national attention when he won the 1999 USGA Junior Amateur Championship, and he was 1999 AJGA Player of the Year with victories in the Western Junior and North & South Junior.
He was a first team All-American at Oklahoma State in 2002 and 2003, and was the Big 12 Player of the Year in both of those years. He played on the 2002 World Amateur and Palmer Cup teams, and his eight college victories included the 2003 Big 12 Championship.
Mahan was recognized as the college golfer of the year with the 2003 Jack Nicklaus Award and Fred Haskins Award, and he also received the Ben Hogan Award.