Japan's Kei Nishikori advanced to the second round of the Western & Southern Open men's singles after beating Russia's Andrey Rublev in straight sets on Monday.Nishikori, ranked 23rd in the world, claimed a 7-5, 6-3 win over the No. 37 Russian at Lindner Family Tennis Center. The 28-year-old Japanese allowed Rublev to tie several times and break him twice, but converted four of his own six chances.Rublev fought back from a three-point deficit and leveled at 5-5 in the first set, but Nishikori took the next game and broke Rublev's serve in the decider.In the second set, the pair traded games…READ FULL ARTICLE