Nijel Amos of Botswana, David Rudisha of Kenya and Musaeb Balla of Qatar cross the finish line in the men's 800m semi-final during day two of the IAAF World Championships Beijing 2015 at Beijing National Stadium on August 23, 2015 (Getty Images)

The highlights of day two at the IAAF World Athletics Championships was seeing David Rudisha back to his commanding best in the men's 800m semi-finals, but it was a shock to see the Ethiopia's Mohammed Aman and Botswana's Nijel Amos fail to make the finals.

Rudisha, the London 2012 Olympic Games champion, lead the second semi final through a moderate pace round the first 400m in 54.04 to win comfortably in 1:47.70 and qualified for the final.

Behind him in the slowest of the three semi-finals, the reigning Commonwealth champion Nijel Amos lost out on the second automatic qualification spot to Qatar’s Musaeb Abdulrahman Balla, who caused the biggest upsets of the night edging Amos with 1:47.93 to 1:47.96.

Aman, with a fast time of 1:45.01, was poise to progress to the final as one of the fastest non-automatic qualifiers from the first semi-final but was disqualified for obstructing Thijmen Kupers of the Netherlands and Nader Belhanbel of Morocco took up his spot in the final with his 1:45.28.

Meanwhile Kenya drew attention to their future prowess outside their traditional middle and long distance events as the duo of Nicholas Bett and Boniface Tumuti  swept into the men's 400m hurdles final.

Bett finished second to American Michael Tinsley (48.47) in his semi-final in 48.54 while Tumuti won his semi-final in 48.29, his second successive personal best of the championships and just 0.06 away from Erick Keter’s national record which has stood for 22 years since the Stuttgart 1993 world championships.

Ethiopians Dawit Seyaum and Genzebe Dibaba; Moroccans Malika Akkaoui and Rababe Arafi, and Faith Kipyegon of Kenya also progress to the women's 1500m final.