Allyson Felix will get one more last lap with surprise entry in women's 4x400 relay at World Championships

Surprise!

Allyson Felix's last lap wasn't her last lap after all.

While Day 8 of the World Athletics Championships were unfolding Friday in Eugene, Ore., the NBC Olympics Twitter feed announced that Felix will run the preliminary round of the women's 4x400 meter relay on Saturday night.

For weeks it had been advertised that Felix's last race on the global stage would be in the mixed 4x400m relay, which took place last week, on the first night of the Championships. The 36-year-old announced in April that this would be her last competitive season.

Felix ran the second leg of the relay in the medal race and got the baton around in a solid 50.15 seconds; the U.S. won the bronze medal.

It was the 19th Worlds medal of her illustrious career, more than any man or woman in history.

Assuming the Americans make out of the preliminary race, the U.S. could have 400-meter hurdles world-record holder Sydney McLaughlin and fellow long hurdles star Dalilah Muhammad as part of the four-woman group for the final race, virtually guaranteeing a medal.

Even if Felix only runs the prelim she will still get a medal, meaning she'd retire with an even 20 Worlds medals.

The women's 4x400m prelims begin at 8:10 p.m. ET Saturday night.