There were also wins for Stan Wawrinka and Serena Williams
Andy Murray continued his unbeaten streak in Grand Slam matches with a straight-sets win overnight in New York at the US Open.
The Wimbledon champion defeated Marcel Granollers in straight sets in under two-and-a-half hours. The match finished 6-4, 6-1, 6-4.
It was an unbeaten Day Four for the men's top seeds. Stan Wawrinka and Kei Nishikori also reached the fourth round in straight sets and four sets respectively.
Former champion Juan Martin del Potro also continued his return from wrist problems. The Argentine defeated America's Steve Johnson in straight sets.
In the women's draw, the Williams sisters both advanced to the third round with straight sets wins. Venus got the better of Julia Goerges, while top-seed Serena defeated Vania King.
There were also wins for Agnieszka Radwanska and Simona Halep, but former champion Sam Stosur lost in straight sets.
Friday sees Novak Djokovic and Rafael Nadal in action in the men's draw, while Angelique Kerber and Madison Keys compete in the women's tournament.