NEW YORK, Sept 4 (Reuters) - South African Lloyd Harris reached the fourth round of a Grand Slam for the first time on Saturday with a 6-4 6-4 6-4 victory over Canadian world number 10 Denis Shapovalov at the U.S. Open. The 22-year-old Shapovalov, seeded seventh at the hard court major this year, came into Saturday"s match at the Louis Armstrong Stadium having lost his only previous meeting against Harris in March. Since that Dubai meeting, the South African, 24, has made rapid strides in his career, defeating 20-time Grand Slam champion Rafa Nadal in Washington last month and has climbed up to a career-best ranking of 46th. On Saturday, Harris took his chances against an error-prone Shapovalov, the quarter-finalist last year at Flushing Meadows, breaking the left-hander"s serve five times to wrap up the match in two hours and 12 minutes and make the second week of a Grand Slam for the first time. "The fourth round is obviously a major accomplishment for me, it"s my first one ever, and I"m looking forward to the next one," said Harris, who will next face big-serving American Reilly Opelka. "I can"t wait to be back. Everything has been coming together this season. I feel confident in my game and I want to keep the momentum going." Shapovalov had a chance to become the fourth Canadian to make the fourth round at this year"s U.S. Open but was undone by 40 unforced errors while hitting 24 winners. In response, Harris committed 23 unforced errors while hitting 27 winners. Shapovalov had breakpoint chances in the fourth and sixth games of the opening set but Harris saved them before converting his lone opportunity in the seventh game. The Canadian took early breaks in both the second and third sets but was left frustrated as Harris rallied each time to level things before seizing his opportunities.