Former world No. 4 Kei Nishikori advanced to the third round of the Citi Open on Wednesday following a straight-sets win over American qualifier Donald Young.After receiving a first-round bye in the men's singles, the seventh-seeded Nishikori, one of four past champions in the men's field, slammed eight aces while converting three of five break points to take down Young 6-3, 6-4 at Rock Creek Park Tennis Center.The 28-year-old Japanese, currently ranked 20th, remains undefeated in seven match-ups with the No. 234 Young."It's been a while since I played on a hard court and I was nervous, but…READ FULL ARTICLE