Usain Bolt remained on course to win a third gold medal at the 15th world athletics championships on Saturday when Jamaica easily qualified for the final of the men's 4x100 metres relay.

Bolt did not run in Saturday's morning heats but will take his place in the evening finals after his team mates set the fastest qualifying time at Beijing's national stadium. Nesta Carter, Asafa Powell, Rasheed Dwyer and Nickel Ashmeade won their heat in a slick time of 37.41 seconds, the fastest time in the world this year.

France finished second behind Jamaica in 37.88, recording the second fastest time overall, while the United States, who loom as the biggest threat to Jamaica for the gold medal, set the third best time of 37.91 in winning their heat.

Bolt has already won the individual 100m and 200m events and is attempting to complete the sprint treble for the third time at the world championships after previously achieving the feat in 2009 and 2013.

Jamaica also topped the qualifiers for the women's one-lap relay when the ace team of Sherone Simpson, Natasha Morrison, Kerron Stewart and Shelly-Ann Fraser-Pryce, the individual 100m champion, won their heat in 41.84.

The U.S. won the other heat in 42.00 to qualify second fastest overall after a blistering second leg run from Allyson Felix.

As expected, the Americans set the fastest qualifying times for both the men's and women's 4x400m events, which will be decided on Sunday night, the last day of the championship, while Ashton Eaton maintained his lead in the decathlon after seven of the 10 events.

Eaton, the reigning world and Olympic champion and world record holder, set the second fastest time in the 110m hurdles, and threw the discus 43.34 metres.

Second-placed Canadian Damian Warner finished just ahead of Eaton in both disciplines to trim the deficit but still trailed the American by 131 points with just the pole vault, javelin throw and 1500m to go.

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