The US team are ranked third in the world
The United States men's volleyball team reached the Olympic quarter-finals after coming from behind to beat Bulgaria 27-29 25-21 25-14 26-24.
It win was an emotional victory for the US, with their coach Hugh McCutcheon mourning the shocking murder of his father-in-law in Beijing.
McCutcheon has temporarily handed over control of the team to assistant coach Ron Larson and did not watch the match.
Russia and Poland also went through, while China kept their hopes alive.
Poland made it three wins out of three by defeating Serbia, and Russia also maintained their unbeaten record with a comeback victory over reigning Olympic champions Brazil.
China beat Japan in a five-set thriller played in front of a partisan 16,000 crowd.