World No.2 Andy Murray and Japan’s Kei Nishikori advanced into the third round after defeating their respective opponents at the US Open tennis tournament here.

Murray on Thursday brushed aside Spain’s Marcel Granollers 6-4, 6-1, 6-4 to advance, while Japan’s Kei Nishikori edged past Russia’s Karen Khachanov 6-4, 4-6, 6-4, 6-3.

In a match played under the closed roof of Arthur Ashe Stadium on Thursday afternoon, Murray, the 2012 champion and 2008 finalist, controlled the proceedings from start to finish against an opponent who lacked the firepower with his serve and ground strokes to pose a serious threat.

Granollers was most competitive in the first set, which took one hour and seven minutes, going down an early break but managing to get the match back on serve at 4-5.

The 29-year-old Murray, however, then reeled off seven of the next eight games to take a commanding two-sets-to-love lead and finished off the contest in two hours and 22 minutes with one final service hold.

The Scotsman won easily even though his first-serve percentage went from bad to worse throughout the contest, as he put 49 per cent of his first serves in play in the first set and made 46 percent and 36 per cent in the second and third sets, respectively.

"(The end of the first set) was very tough. I didn’t play that well during that period and managed to come through it thankfully and play some good stuff in the second and third sets," Murray said in the post-match press conference.

"I served at like 40, 42 percent first serves or something and still won in straight sets. I must have been doing other things well," he added.

With his sixth straight win over Granollers, Murray ran his career record over the world No.45 to 8-2.

Murray will now take on the winner of the second-round match pitting France’s Gilles Simon against Italy’s Paolo Lorenzi that was scheduled to start afternoon but did not start due to steady rain.

The second-highest ranked player in Murray’s quarter of the draw, Japanese sixth seed Kei Nishikori, was scheduled first on Louis Armstrong Stadium and managed to find a window to complete his victory over Khachanov.

The big-hitting 20-year-old Russian threw down a score of aces and won 83 percent of his first-serve points, but he still had his service broken five times by Nishikori, one of tennis’ best returners and counter-punchers.

The Japanese star, the US Open runner-up in 2014, will next square off against Frenchman Nicolas Mahut, who defeated countryman Paul-Henri Mathieu 6-4, 6-4, 6-2.

Eighth-seeded Austrian Dominic Thiem also moved into the third round with a 6-4, 6-3, 6-2 win over Lithuania’s Ricardas Berankis.

In results involving top women players, Romanian fifth seed Simona Halep defeated Czech Lucie Safarova 6-3, 6-4, sixth-seeded American Venus Williams cruised past Germany’s Julia Goerges 6-2, 6-3 and 10th-seeded Czech Karolina Pliskova topped Paraguay’s Montserrat Gonzalez 6-1, 7-5.