Kei Nishikori hits out against Marco Trungelliti in the first round of the US Open on Monday. Photo: Danielle Parhizkaran/USA TODAY Sports

NEW YORK – Kei Nishikori became the first man to advance to the US Open second round as the 2014 finalist beat qualifier Marco Trungelliti, who was forced to retire with the Japanese leading 6-1 4-1 on Monday.

Nishikori’s serve clicked from the start, and the seventh seed won 90 percent of his first-serve points while never facing a break point against the Argentine in 47 minutes on Grandstand.

Next up for Nishikori is a second-round clash with Thiago Monteiro or Bradley Klahn.

Meanwhile, Latvian 12th seed Anastasija Sevastova dispatched an error-prone Genie Bouchard 6-3 6-3 to reach the second round of the US Open.

Bouchard struggled with her accuracy, committing 27 unforced errors and double faulting four times, in the match which drew a big crowd to Court 5.

Sevastova, a semi-finalist in New York last year, was sharper throughout, and blazed a crosscourt forehand winner past Bouchard’s outstretched racket on match point.

Former world number five Bouchard, who reached the Wimbledon final in 2014, has struggled all season.

She is now ranked a lowly 119, and her loss on Monday was her 12th in a row.