Britain through to women's 4x400m final

Merry and Fraser were third and fourth in the 400m final

The USA look like the team to beat in the women's 4x400m relay but Great Britain showed they are a threat by winning their heat.

The Americans cruised to a comfortable victory in the first leg in a time of 3:23.95 followed by Cuba in 3:25.22.

Only two qualified by right from each heat and Britain faced a tough second heat which included Jamaica, Russia and Italy.

Helen Frost ran a solid first leg and handed over to Donna Fraser with Britain in third position.

But Fraser, fourth in the individual race, ran a fantastic leg, and sent Allison Curbishley away on the third leg neck and neck with the Jamaicans.

There was barely a metre between Russia, Jamaica and Great Britain when Katharine Merry took over for the final leg, but the individual bronze-medallist brought Britain home clear in 3:25.28 ahead of Jamaica in second place.

Merry, hoping to grab her second medal in Sydney after taking bronze in the women's individual 400m race, said: "I was tired today.

"But I knew we wouldn't find a problem getting off on the relay - the girls gave me such a good lead. We had an absolute cracking start."

Nigeria should not be discounted either and recorded the fastest time in winning the third heat in 3:22.99 ahead of Australia who broke their national record.

Russia and the Czech Republic went through as the two fastest losers.