Usain Bolt chases 'double treble'

Usain Bolt, the greatest sprinter of all time, will look to top off another epic Olympic campaign on Saturday when he goes in the 4x100m relay, chasing his third gold medal of the London Games.

The Jamaican, who already has the 100m and 200m golds under his belt, is eyeing a second consecutive Olympic golden treble after winning the 100m, 200m and 4x100m in Beijing.

Elsewhere on the final night of action in the Olympic Stadium, the decibel count will be off the charts as home favourite Mo Farah bids to add the 5,000m title to his 10,000m gold.

Bolt came to London with questions swirling over whether he was still the dominant force in world sprinting but he ran the second fastest time in history to win the 100m, and added the 200m title on Thursday.

But the Jamaicans will not have it all their own way, missing the injured Asafa Powell from their stellar line-up in a likely two-way battle with a powerful US team.

"It could be a world record but you can never say because it's a relay and it's a baton so you never know. But for me, we're just going to go out there and enjoy ourselves and run as fast as possible and it will be a good race to close the show again," said Bolt after winning the 200m.

Farah's first gold of these Games came in a glorious hour for Great Britain last week, after Jessica Ennis won the heptathlon and Greg Rutherford took a surprise long jump title.

The Somalian-born Farah, whose 10,000m victory was Britain's first ever over the distance, was caught up in some jostling in Wednesday's semifinals as he battled fatigue, but he made it safely through.