American Grant Holloway took world gold in the 110m hurdles after a last-minute private run by the injured reigning Olympic champion, Jamaican Hansle Parchment in Eugene, Oregon.
Holloway, 24, won in 13.03 ahead of another American, Trey Cunningham (13.08).
A few minutes earlier, Parchment had injured himself on the Hayward Field track in the final moments of preparation before the start, overcoming an obstacle.
Another gold favorite, American Devon Allen, best world performer of the season (12.84), was disqualified for false start.
The road was then cleared for Holloway, who brought the United States a sixth world title on the second day of racing.
The American hurdler had already set the best time in the playoffs the day before and shortly before in the semifinals.
Bronze medal the unexpected Spaniard Asier Martinez (13.17).
