"After the semi-final I knew I needed to bring it home. I needed a better race."
Czech Republic's Zuzana Hejnova became the first woman to successfully defend her 400 metres hurdles title, after 14 editions of the world championships, when she won gold at the Bird's Nest Stadium on Wednesday.
She produced a dominating and controlled performance to come home two metres clear of Shamier Little, the United States champion, in a world leading 53.50 seconds.
Little, the 20-year-old U.S. collegiate champion, took silver on her worlds debut in 53.94, with her team mate Cassandra Tate winning bronze with 54.02.
The threat from Jamaica's Kaliese Spencer vanished at the second hurdle, where the Commonwealth champion blundered, lost all momentum, and was never able to get back into the race, trailing home last of the eight finalists.
The 28-year-old Hejnova, drawn in lane five, was clearly in the lead by the time of the seventh flight and held a three-metre advantage into the home straight which was never seriously challenged.
"It was a very hard final for me because I was the defending champion," Hejnova said. "It got very tough at the end."
The long-legged Little, who seemed to struggle in the preliminary rounds, suffered from being in the inside lane.
"My lane today was as bad as in the semi but it did not matter," she said.
"After the semi-final I knew I needed to bring it home. I needed a better race," added the student at Texas A&M University. "I love this world championships atmosphere. It is like they are going crazy."
Tate was satisfied with her bronze, saying: "I'm happy to come home with a medal. I had a few mishaps and hit a few hurdles, but I wouldn't change anything."