LONDON — The moment and the crowd of 55,900 at London Stadium were his, and Usain Bolt was inches from a clean getaway.

But on Saturday night, there would be no pitch-perfect ending to what Bolt insisted was the final individual race of his unparalleled career.

The gold medal in the 100 meters at the world track and field championships went instead to Justin Gatlin, the 35-year-old American who has long been Bolt’s foil and who had not won a 100 world title since 2005. Gatlin has served two doping suspensions in his career, and the spectators booed him before the final, just as they had in the early rounds.

Running far outside in Lane 8, Gatlin finished in 9.92 seconds, reeling in Christian Coleman, a 21-year-old countryman he has mentored, with a final surge. Gatlin screamed with delight and put an index finger to his lips as if to silence the crowd when the results of this very close race appeared on the scoreboard.

Coleman, in his first world championships, took the silver in 9.94 seconds. The bronze went to Bolt, whose 9.95 was his slowest time in a major 100-meter final. It was also a big stride or two removed from his world-record 9.58, set in Berlin in 2009.

“I’m just sorry I couldn’t end it on a winning note,” said Bolt, who will turn 31 this month.

It seemed hardly fitting, but then neither life nor track meets follow a script. Bolt’s season turned out to be one too far, after his triple-gold-medal performance at last year’s Olympics in Rio de Janeiro.

In 2017, and above all on Saturday night, he simply did not deliver the required valedictory speed. But he insisted the defeat had not altered his retirement plans.

“It doesn’t change anything for me,” Bolt said. “I think I lost the race to a great competitor.”

Referring to Coleman, he said: “I came in third to a young kid that is coming up. He has a great talent and great future ahead of him. So no regrets. I came out and did my best. I was always going to end no matter what happened — win, lose or draw. I was always going to walk away. I’ve done all I can do for the sport and for myself. It’s time to go.”