There was, perhaps, a moment of uncertainty for Allyson Felix.
After a lightning-fast start in the 400 meters at the track world championships on Thursday, Felix appeared to ease up along the backstretch.
Her hesitation was only momentary. Coming around the turn, the former USC star hit the gas to pull away for a convincing victory at Bird's Nest stadium in Beijing.
"I wanted to control the race," she said. "I wanted just to trust in my fitness, because I knew I had it."
The win gave Felix her ninth world championship -- a mark that stood tied for the most ever until 15 minutes later, when Usain Bolt earned his 10th championship in the 200 meters.
Coming into this meet, the 29-year-old had bypassed her trademark 200 to compete at the longer distance. She becomes the first woman to win world championships in the 200 and 400.
Shaunae Miller of the Bahamas finished second, and Shericka Jackson of Jamaica took the bronze.