In QF1, Michael Johnson hustled through a fast 200, coasted around the curve relaxed but moving, and almost jogged in the final 100, running just fast enough to cross the line first in 45.31, ahead of Piotr Haczek of Poland and Avard Moncur of Bahamas, both of whom PB'd in 45.43. Fourth to loud applause was Aussie Casey Vincent in 45.45.
In QF2, Jamaican Davian Clarke ran the curve hard and passed Antonio Pettigrew of the U.S. in the straight (though Antonio was loafing the last 50m) to win in 45.07, with Saudi Hamdan Al-Bishi and Jamaica's Danny McFarlane third and fourth. 1996 Olympic bronze medalist Davis Kamoga of Uganda was 6th in 45.74.
American Alvin Harrison ran away with the third quarter-final, winning in 44.25 (!), a full eight metres ahead of Greg Haughton of Jamaica, with Alessandro Attene of Italy and Patrick Dwyer of Australia also advancing.
Poland's Daniel Mackowiak took the final race in 45.01, a PB, finishing strongly ahead of Hendrick Mokganyetsi of South Africa, Briton Daniel Caines and Sanderlei Parrela of Brazil (second in last year's Worlds). Sixth and out of it was Mexico's Alejandro Cardenas (third behind Parrela in Sevilla) and last was five-time Asian champion Ibrahim Ismail of Qatar.