Chad le Clos crashed out in a shocking defeat on Thursday night, on day six of the World Aquatics Championships in Budapest.
Having reclaimed the global 200m butterfly title earlier in the week, Le Clos was aiming to become only the second man after American great Michael Phelps to lift the 100m crown three times in succession.
He finished seventh in his two-length semifinal in 51.48, however, and was eliminated ahead of the medal contest as he missed out on a place in the final by 0.17.
Earlier, the rest of his compatriots bombed out in the opening rounds of their events.
Douglas Erasmus ended 31st overall among the entrants in the men’s 50m freestyle heats in 22.56 seconds, while Zane Waddell trailed home in 45th position in 22.86.
In the women’s 50m butterfly event, teenager Erin Gallagher also failed to progress by grabbing 34th spot in 27.36.
Though she put up a fight in the 200m breaststroke, Caitlin Randle also crashed out by touching the wall in 27th position among the competitors in the opening round in 2:17.14.
Distance specialist Kate Beavon was 29th in the first round of the women’s 800m freestyle contest in 8:58.31.