Nairobi — Emmanuel Korir will not defend his 800m world title after finishing fourth in the Heats on Tuesday evening, crushing out alongside veteran Ferguson Rotich as youngsters Emmanuel Wanyonyi and Alex Ng'eno pulled through.

Korir, who win the title in Oregon last year, finished fourth in his heat and couldn't squeeze into the three non-automatic qualification slots, while Rotich finished sixth in his heat after struggling all through.

Both Wanyonyi and Ngeno won their respective Heats in commanding fashion and have progressed to the semi-final.

Wanyonyi, the 2021 World U20 Champion was the first out on the tartan in Heat One and he put up a brilliant display to win in a time of 1:44.92, the only one to dip under 1:45 in all the seven Heats.

He had been boxed as they went in for the bell, but he managed to shake off and come on the outside, before putting up a good sprint at the home stretch and topping it up with a small fistbump to celebrate at the end.

It was more or less the same kind of plan for Ngeno, who showed his intent with a good performance at the Kenyan trials. Much more than Wanyonyi though, he put on a powerful acceleration at the home stretch to ensure he occupied the first position in 1:47.63.

Ferguson struggled in his Heat from start to finish and despite a late attempt to surge, he couldn't cover the ground ahead of him and timed 1:46.53.

Korir clocked a season's best time of 1:46.78, but the struggles he has faced this year were clearly visible as he couldn't fire in time to dip into at least the top three automatic slots.