Began playing at age seven...First name nickname is Jimmy and his junior coach Alen Ma called him that at age nine...Father, Kuo Yen, is retired but helps coach his son...Mother, Mei Fung Chao, is a doctor...Has one older sister Yeu Chen...A member of ITF Tournament Team, funded by Grand Slam Development Fund, as a junior and represented Chinese Taipei at team competitions in three age groups (14-under, 16-under, 18- under)...Compiled an impressive junior career, reaching a career-high junior ranking of No. 3 in 2001 before finishing No. 5...Reached final at Australian Open (l. to Janko Tipsarevic) and US Open (l. to Gilles Muller) and semifinals at Wimbledon (l. to Roman Valent) junior tournaments that year...In his junior career, won eight singles and four doubles titles...Has a 15-5 career Davis Cup record (10-3 in singles) in nine ties since making his debut in 2001.