Defending champion Russia and Brazil have secured spots in the second round of the women's volleyball world championship, but China is on the verge of elimination after South Korea handed the Athens Olympic champion its second defeat on Sunday.

Alongside Russia and Brazil, Italy, Japan, Serbia and South Korea also booked their places in the second round that involves 16 teams.

South Korea pulled off the biggest upset on Day 3 with a 25-22, 25-23, 25-23 victory against China.

"I am overjoyed after this win, but it is just one victory. We have to go on work hard," said South Korean coach Park Sam-Ryong.

Kim Yeon-Koung was the star for South Korea, as she dominated play with her versatility and power game. She scored 24 points and teammate Hwang Youn-Joo added 16 points.

The Chinese, who went down to Turkey in four sets in their opening match before nabbing a straight-set victory over Canada, took the upper hand against the South Korean but were unable to keep it.

"We tried our best, but South Koreans played perfect tips and won the long rallies," said Yu Juemin, head coach of China.

Earlier at Osaka, Russia made quick work of Canada 25-13, 25-16, 25-21. Russia and South Korea both have six points after preserving their unbeaten starts in Pool D.

China, who dropped to 1-2 following the loss, faces a life-and-death battle against the Dominican Republic on Tuesday before taking on Russia on Wednesday.

Japan's third win - a 25-18, 25-7, 25-14 rout of winless Algeria on Sunday - in as many matches guaranteed that the host will finish in the top four in six-team Pool A.

Japan is now tied with Serbia atop the Pool A standings with six points.

Serbia defeated Peru 25-21, 16-25, 25-21, 25-18 earlier at Yoyogi National Gymnasium to secure its spot in the next round. Peru dropped to 1-2.

In Pool B at Hamamatsu, Beijing Olympic champion Brazil defeated the Netherlands 25-19, 25-18, 25-14 to stay unbeaten, along with Italy.

"We played a great match today, especially in terms of serving and blocking," said Brazil coach Jose Guimaraes. "We really understood that this was a key match and we prepared well for it. I was very happy that we executed what we planned to do."

The Dutch team fell to 1-2. Italy cruised to a 25-9, 25-7, 25-21 victory over winless Kenya.

At Matsumoto, the United States took sole possession of the Pool C lead with a 3-0 mark after beating Germany 25-23, 26-24, 25-17.

In the first match of the day, Cuba picked up its first win, overcoming Kazakhstan 3-2.

"We are in a situation of do-or-die, it's like we're competing for the World Championship in every match," said Cuba coach Juan Gala Rodriguez.

"I hope our team continues to play at a high level. We can't afford to let up," he added.

After a rest day on Monday, the first round will resume on Tuesday with two more rounds play with nine second-round slots still wide open.

The world championship involves four six-team groups and a round-robin schedule in the first round. The top four teams in each pool advance to the second round for crossover play. The semifinals and finals will be played in Tokyo on Nov. 13-14.