By Bryn Palmer, Sydney

Mark Foster was unable to salvage a medal for Britain's beleaguered swim team as a remarkable men's 50m freestyle final ended with Americans Anthony Ervin and Gary Hall Jr dead-heating for the gold medal.

Both Americans were timed at 21.98 secs to share the shortest freestyle sprint title, with flying Dutchman Pieter van den Hoogenband taking the bronze in 22.03 secs, to add to his golds in the 100m and 200m freestyles.

Foster, the 30-year-old from Bath competing in his fourth Olympics, finished seventh in 22.41 secs.

"I am disappointed, because I have swum faster than that on three or four occasions in hard training lately," he said.

"I started off well and didn't feel too bad after 35 metres, but it just wasn't there tonight, and it has not been there all week."

There was also disappointment for Russian Alex Popov who failed in his bid for gold in three consecutive Olympics by finishing sixth.

In the men's 100m butterfly final, Swede Lars Froelander upset the odds to deny the host nation another anticipated gold medal, touching first in 52.00 seconds in front of Australians Michael Klim, who won silver to add to his two relay golds, and Geoff Huegill, who had set the Olympic record in the semi final but was unable to match it in the final.

In the women's 800m freestyle final, Brooke Bennett of the USA set a new Olympic record of 8:19.67 to take gold, edging out Ukrainian Yana Klochkova and fellow American Kaitlin Sandeno, who took bronze.

Romanian Diane Mocanu won the women's backstroke, the opening final of the session, in 2:08.16, with France's Roxana Maracineanu over two seconds adrift in second and Japan's Miki Nakao claiming the bronze.