South Africa's 2003 world high jump champion Jacques Freitag lost his title on Friday as he failed to make it through the qualifying round.
The 23-year-old failed three times at 2.24 metres and with 13 athletes having already successfully jumped 2.24m and only 12 to progress to the final it left Freitag out in the cold.
Freitag admitted that his lack of consistency since he changed his run-up had cost him dearly.
"I changed it in winter training and I have yet to find the consistency that is required to give me enough confidence in the event," said Freitag, who has also changed coach since his triumph in Paris in the 2003 championships.
"Sometimes I have days like today and then there are others where I come out and jump 2.35m with ease.
"My ankle is fine now and I am not too disheartened as I know I will be back."
Freitag has had injury problems since winning the title in Paris only returning for the Olympics last year having just recovered from an ankle injury and it showed as he failed to qualify for the Athens final.
On the Golden League circuit this term he finished fourth in Paris and third most recently in Oslo.
There were no other major surprises as Olympic champion Stefan Holm of Swden qualified on 2.27m.
Among the others to qualify were Canada's two-time world medallist and Commonwealth Games champion Mark Boswell with a season's best of 2.27m and America's Matt Hemingway - who is descended from legendary American novellist Ernest - as he also posted a season's best of 2.27m.