BEIJING - Favourites Cuba and Brazil powered into the women's volleyball semi-finals in straight sets on Tuesday, edging one step closer to their gold medal goals.

Brazil's Fabiana Claudino (C, #9) smashes the ball against Japan's Miyuki Takahashi (L) and Erika Araki (R) during their women's volleyball quarterfinal match against Japan at the 2008 Beijing Olympic Games on August 19, 2008. Brazil won 3-0. [Agencies]

Cuba, which swept their Group A matches, won 26-24 25-19 26-24 against Serbia in the packed Capital Gymnasium, but the Caribbean side almost faltered in the hard-fought first and third sets.

"Although we won, our players had been under tremendous mental pressure. We'll do better than this in the next two matches," said head coach Antonio Perdomo, acknowledging the team's many errors in front of a crowd cheering the underdog.

Brazil's 25-12 25-20 25-16 win was much more comfortable, with their powerful spikes overcoming resistance from a persistent Japanese side, whose players were in tears after the match.

"Yes, I think about that. We are in the medal zone. That's important," Brazilian head coach Jose Roberto Guimaraes said when asked about the team's ambitions for gold.

Brazil did not lose a single set in their Group B matches and the successive wins appear to have made captain Helia Souza even more confident.

"We cannot choose our opponent in the matches ahead, but we'll be prepared to defeat any," Souza said.

In the semi-finals, Brazil will be pitched against the winner of the quarter-final match between defending champions China and Russia at 1200 GMT.

The long-time rivals staged a classic final match in Athens, with China stealing a thrilling win from Russia after losing the first two sets.

The United States will play Italy at 1400 GMT in the last quarter-final match and the winner will meet Cuba for a place in the final.