New York, Aug 30 (IANS): German defending champion Angelique Kerber was given a shock first-round exit at the US Open, losing to Japan's Naomi Osaka 6-3, 6-1.

It took Osaka, ranked 45th in the world, just 64 minutes to send Kerber packing on Tuesday, one year after the German's triumph at Flushing Meadows, reports Xinhua news agency.

Osaka hit hard from both sides and struck 22 clean winners in the match while Kerber, the first defending champion to lose in the US Open's first round since Svetlana Kuznetsova of Russia in 2005, was in a different league.

Kerber's confidence was shot to pieces in the second set and Osaka was relentless to record the biggest win of her tennis career.

A year ago on the same Arthur Ashe Stadium court, Osaka squandered a 5-1 lead in the final set and lost to American Madison Keys 7-5, 4-6, 7-6 (3) in a third-round match.

"When I stepped on the court and I heard all the people and I saw how big the stadium was, I got a little bit freaked out, but I tried to hold it in," the Japanese teenager said.

"I felt the same type of nerves come up 4-1 in this match, so I wanted to tell myself just to keep playing how I was playing and not let the nerves get over me as much as last year," she said.

"The experience last year helped me this year. I feel like I know that I can play with the top players now, so I don't have to be as nervous as I was today."