US track legend Allyson Felix has deferred her retirement to run heats for the women's 4x400m relay at the World Athletics Championships, it was confirmed Friday.

"Allyson Felix will run the 4x4 prelims," a US team official told AFP in Eugene.

To much fanfare, Felix had initially signed off her glittering career with a 19th world medal as she helped the US team to bronze in the 4x400m mixed relay in Hayward Field on the first day of action of the worlds a week ago.

It was thought that the bronze had brought the curtain down on a stellar career that saw Felix make her world championship debut back in Paris in 2003 at the age of 17.

Felix had initially signed off her glittering career with a 19th world medal as she helped the US team to bronze in the 4x400m mixed relay

Her first major championship medal came when she won 200m silver at the 2004 Athens Olympics, the start of an unprecedented glut of medals in the 200m, 400m and as a member of the often dominant US relay team.

Her overall world tally currently stands at 19 medals (13 gold, three silver, three bronze), including four individual golds.

But there could be another one, should she take part in the 4x400m relays, heats of which are scheduled for Saturday, with the final on Sunday.

Among Felix's staggering medal haul are three Olympic and five world golds as part of US 4x400m winning teams.