He won his first doubles title at the RCA Championships in 2009 with partner Andy Roddick and reached the third round of the Wimbledon singles in 2008.
He helped Vanderbilt reach the finals of the NCAA Men's Tennis Championship.
He features a right-handed forehand and two-handed backhand.
His father Robert is a pilot, and his mother Joyce is a tennis instructor.
Rafael Nadal beat him in the third round of the 2005 Australian Open.