Andy Murray highlighted an eventless day at the US Open tennis tournament with all the big names winning their respective matches at the Flashing Meadows.The second seeded Murray thrashed Bulgarian 22nd seed Grigor Dimitrov, winning in three sets 6-1, 6-2, 6-2 and will join Swiss third seeded Stan Wawrinka, Japanese sixth seeded Kei Nishikori, and Argentine Juan Martin del Potro as quarter finalists.Murray needed only two hours on the Arthur Ashe Court to beat Dimitrov here on Monday.Japanese 26-year-old fourth seed Kei Nishikori won in three sets 6-3, 6-4, 7-6 against twenty-first seeded Croatian Ivo Karlovic.Before the triumphs of Nishikori and Murray, Wawrinka has also reached the quarters for the fifth time, his fourth time in a row, beating Illya Marchenko from Ukraine 6-4, 6-1, 6-7 (5), 6-3.Del Potro will face Wawrinka in the quarters, after his eighth seeded Austrian rival Dominic Thiem withdrew while trailing 3-6, 2-3 in the second set with a right knee pain despite receiving assistance from the physiotherapist.