Team Great Britain set a world record of 3 min 51.43 sec in the men's 4x100m freestyle relay, claiming gold after surging past Australia and China Wednesday at the Water Cube.

"We've had amazing achievements, and it is an amazing feeling to get on the top of the podium," said Briton Matt Walker.

"The makeup of the team has changed, but for me this is the third (medal) we've won," said teammate David Roberts. "We are the best team in the world, and tonight was about proving it."

Wang Xiaofu, who swam the third leg in China's relay line-up, did not seem overly disappointed. "All our four swimmers put on an excellent performance; and we reached the target set by our coach."

On the 4th day of swimming competitions, the Water Cube saw nine countries share 12 gold on offer, with the United States, Britain and Russia bagging two each.

American swimmer Lantz Lamback won gold in the men's 100m backstroke S7 and smashed the world record he set in the morning heat by 1.97 sec.

"I had a good turn I held on till the turn and then I went hard," Lamback said.

His compatriot Roy Perkins stopped Brazilian Daniel Dias' gold rush, taking gold in the men's 50m butterfly S5.

"I am satisfied that I had a personal best, being on the podium is already a victory," said Dias.

China's He Junquan finished with a bronze.

Swimmers compete for another 13 gold today at the Water Cube.