NEW YORK - World No 1 and defending champion Naomi Osaka of Japan overcame the second set slump to take down the unseeded Anna Blinkova of Russia in three sets and advanced into the women's singles second round of the US Open on Tuesday.

The victory didn't come easily, however, as the top seed had to dig deep to claim the victory at 6-4, 6-7 (5), 6-2.

"I don't think I've ever been so nervous in my life," Osaka said. "I don't think I ever really found my rhythm, but I just fought as hard as I can."

A year ago on this same stage, Osaka capped off a stunning fortnight that saw her drop just one set to win the US Open title. She also won the Australian Open this season.

Coming up next in the second round for Osaka will be Poland's Magda Linette, who lifted her first career WTA trophy at the Bronx Open this past weekend. Linette beat Astra Sharma of Australia at 6-3, 6-4 to advance.