Emphatic Osaka powers into China Open round two

US Open champion Naomi Osaka needed just 68 minutes to power into round two of the China Open with a dominant performance over Kazakh qualifier Zarina Diyas on Monday.

Also safely through on Beijing's outdoor hard courts is another reigning Grand Slam champion, Australian Open winner Caroline Wozniacki.

With world number one Simona Halep retiring from the tournament with a back injury and Serena Williams absent, Osaka and Wozniacki are among the favourites.

The Japanese Osaka, who is enjoying a breakthrough season after stunning Williams to win in New York, breezed past a bewildered Diyas 6-4, 6-3.

Osaka, a rising star of tennis at just 20, plays unseeded American Danielle Collins next.

Former world number one Wozniacki was similarly emphatic with a 6-2, 6-3 demolition of Switzerland's Belinda Bencic.

The world number two Dane was never in serious trouble against 41st-ranked Bencic, although it has not always been like that down the years, Bencic winning four of their past six meetings.

Wozniacki will play Croatia's unseeded Petra Martic in round two. It was a case of seventh time lucky for another former number one, Garbine Muguruza, as the Spaniard set up a meeting with Aryna Sabalenka of Belarus.

Muguruza, who is now down in 15th in the world, made a fast start as she hammered Ekaterina Makarova 6-0, 6-4, making the seventh match point count against the Russian.

Elise Mertens, the 15th seed from Belgium, suffered a surprise defeat to home player Zhang Shuai, the Chinese winning 6-1, 3-6, 6-3.