USAIN Bolt and Shelly-Ann Fraser-Pryce secured their third gold medals of the Moscow World Championships when the two 100m and 200m sprint champions anchored Jamaica to victory in the 4x100m relays.
Bolt's task was made easier when American fourth-leg runner Justin Gatlin fluffed his start, stumbled and veered into the Jamaican's lane.
"We could have gotten the Jamaicans," said a rueful Gatlin, runner-up to Bolt in the 100 final.
"I'm disappointed (for my team mates). They deserved more. I think my stumble cost us victory."
The Jamaican quartet of Nesta Carter, Kemar Bailey-Cole, Nickel Ashmeade and Bolt secured the Caribbean nation a hat-trick of world titles in a time of 37.36.
Victory took Bolt's all-time tally to eight gold. That matches American trio Carl Lewis, Michael Johnson and Allyson Felix but the Jamaican moved ahead by virtue of his two silvers from 2007.
Gatlin brought home USA in 37.66 with Canada upgraded to bronze after Britain were disqualified, continuing their relay woes of past championships in which they have often failed to get the baton around a full lap.
The Britons were penalised after a changeover mistake between Harry Aikines-Aryeetey and James Ellington who minutes earlier had told the BBC that the team had "got the changeovers down to a tee now".
The Jamaican women regained the world title from USA, again helped by a costly error. The quartet of Carrie Russell, Kerron Stewart, Schillonie Calvert and Fraser-Pryce streaked to gold in 41.29, the second-fastest time ever run. A mishap on the second and third interchange between Alexandria Anderson and English Gardner, who started her run too soon and had to halt to grasp the baton, effectively ended the USA's victory hopes.
France grabbed silver in 42.73 and it was only a storming final leg from Octavious Freeman that secured an unlikely American bronze, Freeman eating up ground down the home straight with a sizzling run to get into a medal position.
USA set a stunning world record of 40.82 at the London 2012 Olympic Games but none of that victorious quartet featured in the Moscow final, notably Allyson Felix who tore a hamstring in the 200m final and 100m bronze medal winner Carmelita Jeter who was left out.
KENYAN Eunice Sum silenced the Moscow crowd with her 800m victory over home favourite Mariya Savinova after being inspired by compatriot Asbel Kiprop's 1,500m gold in the previous race.
Savinova, the Olympic and defending world champion, was roared round the two laps of the Luzhniki stadium but Sum timed her late burst through the middle to perfection, knocking almost two seconds of her personal best with a time of one minute 57.38 seconds. The Russian was second in 1:57.80 and American Brenda Martinez snatched third (1:57.91) from her compatriot and long-time race leader Alysia Johnson Montano, who threw herself over the line.
"When I saw Asbel win, I told myself let's also try," said triumphant 24-year-old Sum. In the last 100 metres, I saw I was really moving while the others seemed to be stuck. When I took the start I didn't know I was going to run like this or that I could be a winner," added the gold medallist.