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Naomi Osaka of Japan hits a return shot while competing against Julia Goerges of Germany in their third round women's singles match in the China Open at the National Tennis Stadium in Beijing, onThursday. Image Credit: AP

Beijing: Naomi Osaka says an improvement in her focus is behind a run of success that culminated in winning the US Open.

The 20-year-old, who stunned Serena Williams to win her maiden Grand Slam last month, was devastating against 10th seed Julia Goerges of Germany on Thursday, winning 6-1, 6-2 in 65 minutes to speed into the China Open quarter-finals.

Osaka, the eighth seed in Beijing, similarly thrashed unseeded American Danielle Collins 6-1, 6-0 in the previous round and is showcasing the ruthlessness that saw her beat Williams in a controversial New York final.

The Japanese will face home hope Zhang Shuai in the last eight in the Chinese capital after Zhang pulled off a shock in defeating three-time Grand Slam champion Angelique Kerber.

“On the court I have to think ‘focus’ because it’s not something that’s natural to me,” the world No. 6 said.

“It’s something that I’ve been working on throughout this whole year and I think it finally clicked, or at least it’s more consistent.”