London, Aug 11 (IANS): Allyson Felix ran the second leg to help the US win the women's 4x100 metres relay in world record time at the London Olympics Friday.

The US quartet of Tianna Madison, Allyson Felix, Bianca Knight and Carmelita Jeter finished in 40.82 seconds, chopping 0.55 seconds off the old mark set by the German Democratic Republic in 1985, Xinhua reported.

"It's an honour to be part of this team. Who would have thought that we would have had a world record tonight? It's amazing. Our names are going down in history," said Felix.

It is only the second world record to fall on the track in these Games, coming after Davida Rudisha broke the men's 800 metres record Thursday.

Jamaica finished second, while Ukraine won a very creditable bronze medal.

Adding to the US victory on the track, wrestler Jordan Burroughs beat Iran's Sadegh Saeed Goudarzi in the men's freestyle 74 kg final to give America its first gold in wrestling.

These success boosted the Americans' medal total to 94, of which 41 are gold.

Meanwhile China, which had lost its top position to the US Thursday, captured only a silver medal in the day - in synchronized swimming, and was in second place with 37 gold, 25 silver and 19 bronze.

Britain is in third place on 25-15-17, followed by Russia on 15-21-27 and South Korea on 12-7-7.

The second relay of the night at the Olympic Stadium had nine finalists after South Africa had been reinstated after crashing out Thursday, that allowed 'Blade Runner' Oscar Pistorius to make his Olympic debut although the battle for the medals didn't involve the South Africans.

The Bahamas led after the first two laps before Toby McQuay put the US ahead going into the last 400 metres. That only set the stage for greater drama as Roman Millar ran the race of his life to close a three-metre gap on American anchor Angelo Taylor.

Miller caught Taylor with 50 metres remaining and strode onto victory. The Bahamas had finished fourth four years ago, this was ample compensation.

"The US guys know we've been just behind them or thereabouts for a long time, but it's amazing we are finally taking home the gold. This is everyone back home. We can't wait to celebrate," said Miller.

Meseret Defar from Ethiopia produced the fastest turn of speed in the last 200 metres of the women's 5,000 metres to claim her second Olympic gold medal in the event.

Defar, the gold medal winner in Athens in 2004, was able to outsprint Vivian Cheruiyot of Kenya and her fellow Ethiopian, Tirunesh Dibaba to take gold.

There was a Turkish 1-2 finish in the women's 1,500 metres as European champion, Asli Cakir took gold and Gamze Bulut silver with Maryam Jamal from Bahrain in third.

Russia's Tatyana Lysenko set two new Olympic records on her way to gold in the women's hammer throw.

Elsewhere, Tunisia's Oussama Mellouli won the men's swimming marathon in the Serpentine lake to give his country its first gold in London. He is the first swimmer in Olympic history to win medals in both pool and open water.

Mellouli, who won gold in the 1,500 metres freestyle in Beijing four years ago and bronze in the same event in London 2012, touched in 1 hour 49 minutes 55.1 seconds.

Colombia and Latvia also put their names on the gold medal list with victories in the BMX cycling, which is making second appearance in Olympics. Mariana Pajon won the women's event, while Beijing 2008 champion Maris Stromsbergs retained his title in the men's event.

The star-studded US men's basketball team are on the verge of defending their Olympic title after routing Argentina 109-83 in the semifinals. They will face Spain in Sunday's gold medal match.

In hockey, the Dutch women's team won their second straight Olympic gold after edging world champions Argentina 2-0 in the final, and Britain captured the bronze medal with a 3-1 win over New Zealand.