The Wimbledon and Olympic champion beat Gregor Dimitrov in just over two-and-a-half hours
Andy Murray has booked his place in the men's quarter-finals at the US Open quarter-finals after a straight-sets win over Gregor Dimirtov.
Murray won the game in just over two-hours, after defeating the Bulgarian 6-1, 6-2, 6-2 at the Arthur Ashe Stadium. It is the fifth time in six years that the 2012 champion has reached the quarter-final stages.
Kei Nishikori awaits Murray in the last-eight. The Japanese star defeated Croatia's Ivo Karlovic in straight-sets. 37-year-old Karlovic was the oldest player to reach the fourth round of a Grand Slam in 25 years.
Juan Martin del Potro's resurgence continued as Dominic Thiem was forced to withdraw in their match. The Argentine won the first set 6-3 and was leading 3-2 in the second when Thiem has to withdraw with a knee injury.
Two-time Grand Slam champion Stanislas Wawrinka completes the men's quarter-final entries. The Swiss number three seed beat Illya Marchenko in four sets.
In the women's draw there was mixed news for the Williams sisters. Serena defeated Yaroslava Shvedova in straight sets, but older sister Venus was beaten by tenth seed Karolina Pliskova despite winning the opening set.
Fourth seed Agnieszka Radwanska suffered a surprising defeat. She lost in straight sets to Croatia's Ana Konjuh 6-4, 6-4.
Romania's Simona Halep also reached the last-eight for the second year in a row. The Romanian defeated Spain's Carla Surez Navarro.
Day 10 sees the start of the men's and women's quarter-finals. The pick of the matches are Novak Djokovic against Jo-Wilfried Tsonga and Roberta Vinci's match with Angelique Kerber.