Felix wins 19th world medal, Kerley scorches 100m heats

American veteran Allyson Felix will hang up her spikes having sealed a remarkable 19th world medal on Friday, while Fred Kerley laid down an impressive marker in the heats for the 100m in Oregon.

Was it the perfect swansong for Felix? Not quite, as she and Kennedy Simon were both reeled in on their resepctive legs, leaving the Dominican Republic to take victory in the 4x400m mixed relay, the Dutch quartet edging the US for silver.

Her bronze is Felix's 19th at world champs in a career that started almost two decades ago and also included 11 Olympic medals.

"It was very special to be able to run in front of a home crowd for my last race," said Felix.

"It was so cool. My daughter was in the stands. It was a night I will cherish."

Felix added: "I've had such good memories. I know it is time and these guys will carry it on into the future.

"I am at peace stepping into this next stage and have tremendous gratitude for this sport."

Two-time Olympic shot put champion Ryan Crouser had high praise for his US team co-captain.

"She's done so much for the sport and especially for women athletes, attracting attention to some really important issues we have in the sport," Crouser said of Felix.

"She's a fantastic athlete, but also a fantastic person. She does stuff the right way, she is just a class act, and kind of the definition of integrity."

In-form Kerley ran a sensational heat-winning 9.79 seconds in a warning to potential rivals for the 100m crown.

He advanced to Saturday's semi-finals along with teammates Marvin Bracey, Trayvon Bromell and defending champion Christian Coleman, who missed the Tokyo Olympics after missing three doping tests.

"It's going to take something fast to win," predicted Canada's reigning Olympic 200m champion Andre