Nishikori hires Michael Chang

Tokyo, Japan ( - World No. 17 Japanese tennis star Kei Nishikori has added former American great Michael Chang to his coaching staff.

The 41-year-old Chang is on board as an advisory coach for 17-20 weeks in his attempt to help Nishikori crack the Top 10. The two have been working together in California for the last two weeks.

Nishikori's full-time coach is still Dante Bottini.

Chang became the youngest man to capture a Grand Slam title when he won the French Open as a 17-year-old in 1989 and reached as high as No. 2 in the world in 1996.

The 23-year-old Nishikori, who will turn 24 on December 29, titled in Memphis and climbed as high as No. 11 in the world this past season.