Usain Bolt led a Jamaican 1-2-3 in Thursday's Olympic 200m final
Jamaica's sprint kings will enter the home stretch of their golden Olympic campaign on Friday after Usain Bolt's historic defence of his 100m and 200m crowns.
A day after Bolt sprinted into the pantheon of Olympic legends by becoming the first man to win back-to-back 100m and 200m titles at consecutive Games, Jamaica's men return to the track for the 4x100 relay.
Bolt, who led a Jamaican 1-2-3 in Thursday's 200m final, may be rested for the opening round of the relay, although the Caribbean islanders should qualify for the final with ease given their awesome strength in depth.
With the pressure off after completing his "double-double", Bolt is targeting more glory in the relay, aiming to sign off with a world record.
"I think there's a possibility," Bolt said, when asked if the existing best mark of 37.10sec could be under threat.
"But you can never really say it, because it's a relay and there's a baton. You never know. But for me, we're going to go out, enjoy ourselves, run as fast as possible. It would be a good way to close the show again."
Jamaica's women's 4x100m relay squad meanwhile are determined to atone for their disastrous performance in the 2008 final, where a bungled changeover almost certainly cost them a gold medal.
The Jamaican quartet -- anchored by 100m winner Shelly-Ann Fraser-Pryce -- qualified fourth fastest for the final, where they will battle powerful teams from the United States and Russia.
In other athletics action on Friday, the United States one-lap specialists will aim to extend their astounding record in the 4x400m relay, where they remain unbeaten on the track since 1984.
Other medals to be decided in the Olympic Stadium on Friday include the women's 5,000m final, where Ethiopian distance legend Tirunesh Dibaba seeks to defend her crown, and the men's pole-vault, where reigning champion Steve Hooker of Australia is favourite.
In men's basketball, the United States and Russia could set up a dream final of the former Cold War rivals with semi-final wins over Argentina and Spain respectively.
Women's hockey sees Argentina take on the Netherlands in the gold medal match on a day when 17 medals will be decided.
The first gold medals of the day came in swimming and sailing.
Tunisia's Oussama Mellouli survived a late surge from his rivals to claim the men's 10km swimming marathon, becoming the first person to win Olympic titles in both pool and open water races following his 1,500m win in Beijing.
Australians Mathew Belcher and Malcolm Page won the men's 470 Olympic sailing gold with New Zealand's Jo Aleh and Olivia Powrie taking the women's 470 title.
Meanwhile, the Games was hit by another drugs test failure when French 5,000m runner Hassan Hirt was reported to have tested positive for the banned blood booster EPO.
A source told AFP that Hirt, who was eliminated in the heats of the event, failed a drugs test on August 3 and had been suspended.