Jamaica reasserted their sprinting dominance with victory in the 4x100m men's relay final AFP

Usain Bolt added relay gold to his list of triumphs at the 2015 World Athletics Championships in Beijing as Jamaica eased to victory in the 4x100m final.

The six-time Olympic champion, who emphatically silenced his doubters by beating controversial rival Justin Gatlin in both the 100m and 200m races earlier this week, was barely tested on the final straight and crossed the line in 37.37secs after Nickel Ashmeade, Asafa Powell and Nesta Carter had laid the foundations for success.

A US team made up of Gatlin, Tyson Gay, Trayvon Bromell and Mike Rodgers initially took silver but were later disqualified after their final baton exchange was adjudged to have occurred outside of the designated zone.

That decision led to hosts China being promoted to second and Canada snatching bronze, but Great Britain disappointingly dropped out of medal contention when their third handover between James Ellington and Chijindu Ujah was botched.

In the women's final, Jamaica asserted their dominance once more as Veronica Campbell-Brown, Natasha Morrison, Elaine Thompson and Shelly-Ann Fraser-Pryce recorded the second-fastest time in history at 41.07secs.

Silver went to the US, while Trinidad and Tobago finished with bronze. Great Britain just missed the cut in fourth although set a new national record of 42.10secs.

One of the most impressive performances inside the Bird's Nest on day eight came in the men's decathlon, where Ashton Easton broke his own world record with 9045 points. Maria Kuchina also won the women's high jump ahead of Blanka Vlasic and Anna Chicherova with a leap of 2.01m. Earlier on, Mo Farah completed his latest double-gold haul with victory in the 5,000m.