Japanese tennis star Kei Nishikori has enlisted the help of Michael Chang as he looks to break into the top 10 in 2014. Chang will join Nishikori's coaching staff for 17-20 weeks in 2014, Nishikori's management team announced on Wednesday. Nishikori has been training with Chang for the last two weeks in California. The 23-year-old Nishikori rose to No. 11 in the world this year and has contributed to a rejuvenation of tennis in Japan. More...