Juniors
In 1987, Wheaton won the 
US Open junior title and was the No. 1 ranked junior player in the US. In 1988, he helped 
Stanford University's tennis team win the 
NCAA team title and received the Block S Award as the most outstanding freshman athlete at Stanford.
Pro tour
Wheaton turned professional on July 4, 1988 and won his first top-level singles title in 1990 at the U.S. Clay Court Championships in Kiawah Island, South Carolina. He was also runner-up in the 
1990 US Open men's doubles (with 
Paul Annacone).
The most significant highlights of his career came in 1991. He won the 
Grand Slam Cup in Munich, beating 
Michael Chang in straight sets in the final 7–5, 6–2, 6–4. He also reached the semifinals of singles at 
Wimbledon (beating 
Petr Korda, 
C?dric Pioline, 
Ivan Lendl, 
Jan Gunnarsson and 
Andre Agassi in the quarterfinals before being knocked-out by 
Boris Becker), and was a men's doubles runner-up at the 
Australian Open (partnering with his former Stanford teammate 
Patrick McEnroe). Wheaton reached his career-high singles ranking of world No. 12 in July 1991.
During his career, Wheaton won three top-level singles and three doubles titles, representing the US in 
Davis Cup (v. Australia, 1993) reached the semifinals or better in either singles or doubles of every Grand Slam tournament, and defeated highly ranked players such as Andre Agassi, 
Jimmy Connors, Ivan Lendl, 
Stefan Edberg, 
Jim Courier, and Michael Chang.