KAZAN, Russia — The first autograph Katie Ledecky signed Sunday after winning the 400-meter freestyle by four seconds was on a piece of paper attached to a clipboard carried by a doping control agent.
Racing on the opening night of swimming at the world championships, Ledecky completed the eight-lap final in 3 minutes 59.13 seconds to give the United States its first and only gold. The effort, 0.76 of a second off her year-old world record, gave Ledecky the three fastest swims in the event. She owns six of the top seven performances, her string interrupted only by Federica Pellegrini’s 3:59.