Merritt clocked a season-best time of 13.04s over the 10 hurdles. It's an event that calls for taking things one step at a time, which is exactly what Merritt did when doctors told him his kidneys were operating at less than 15 per cent and he'd need to retire.
"Pretty much, it mentally destroyed me," Merritt said.
Instead of quitting, he pushed on, even while the disease progressed and chipped away at his fitness and his physique. Racing at 74kg, nearly 3kg lighter than when he set the world record - Merritt ran a near-perfect race, never touching a hurdle and falling by 0.01s to Hansle Parchment of Jamaica for second. Sergei Shubenkov of Russia took gold.
Shubenkov learned about Merritt's condition when he was asked about it at the medallists' news conference.
"You're going to have a kidney transplant and you're here at world championships?" Shubenkov said, shaking his head in disbelief.
Watching at her brother's house in Arizona was Merritt's sister, LaToya Hubbard, who will join Merritt on the operating table on Tuesday to donate her kidney.
"It could've been totally different," Hubbard said. "To see all he's gone through - the pain, the hurt, barely able to get out of bed, barely able to walk. And now, a few months later, he has a medal."
Merritt was all smiles but he knows there are big challenges ahead.
He said he'll take the rehabilitation slowly and, when he's cleared to run again, he'll pretend like he's starting over. The Olympics are less than a year away.
"He's getting a brand new kidney with a new lease on life," his sister said. "He's going to break that record again. I expect to see him in Rio."
Dutchwoman Dafne Schippers will surely also be there after she smashed a 36-year-old European record to win the world 200m title with the fourth fastest run in history.
Schippers, who claimed 100m silver earlier in the week and switched to sprinting from heptathlon after the 2013 world championships, clocked 21.63s as she lunged to deny Jamaica's Elaine Thompson.
It was a remarkable run by Schippers, 23, who eclipsed the European record of 21.71s set by Marita Koch in 1979 and matched by fellow East German Heike Drechsler in 1986.
Only Americans Marion Jones and world record-holder Florence Griffith-Joyner have run the 200m faster than Schippers, who won heptathlon bronze at the Moscow worlds two years ago.
The careers of Koch, Dreschler, Jones and Griffith-Joyner were all mired in doping allegations, but Schippers insisted she had nothing to hide. "I know I'm clean and I work very hard for it," said Schippers. "I do all the dope controls and I don't want to say more than that."
Doping has been in the spotlight after lurid allegations in the build-up to Beijing. Two Kenyan athletes have been provisionally suspended after failing pre-competition tests.
- Agencies
