RIO DE JANEIRO (AP) Usain Bolt is leaving and insists he's not coming back.
How will track and field ever be the same?
The departure of the sport's most electric athlete from the Olympics certainly makes the Tokyo Games feel like a less enticing prospect.
That's hardly the only issue track and field faces as it tries to clean up its act and find some new headliners before 2020.
A look at what the sport might look like - needs to look like? - four years from now.
Somebody will have to claim center stage in the marquee events, the men's sprints. The early candidate is 21-year-old Andre de Grasse of Canada. As a teen, he ran one of his first races wearing basketball shorts and borrowed shoes. He stood up in the blocks while others crouched. It launched his career and led him to signing a big contract with Puma - the same company that sponsors Bolt.
In his own small way, de Grasse may have helped nudge the narrative of Bolt's story in Rio a bit off line. His pushing of Bolt in the 200-meter semifinal - probably unnecessary and maybe even a bit reckless - made for the only real ''race'' the Jamaican faced all week.
Bolt conceded that push-to-the-finish semifinal played into his inability to break his 200-meter world record a night later in the final. A small victory for de Grasse, even if it was a loss for everyone else.
''I was just happy to be part of history with him,'' said the Canadian, who finished second in the 200 final, and third in the 100. ''If people are talking about him, they're probably talking about me, that I was in the same race.''
STARS AND STRIPES
Allyson Felix is 30. She has nine Olympic medals. Six are gold, a record for women on the track. After a long, hard season that didn't go the way she planned, she said Tokyo is nowhere in her thoughts.
''London,'' she said, speaking of next year's world championships. ''That's next on the agenda. As far as the next four years, taking it year by year.''
When Felix goes, who can step in as the next great female American track star? Here's a nod toward 400-meter hurdler Sydney McLaughlin, who made her first Olympics at 17. McLaughlin is the junior world-record holder in the event who really wasn't thinking about the Olympics this year.
She made it to the semifinals at the Olympics. Now, it's back for the start of her senior year of high school in New Jersey.
CRIME, DOPING, CORRUPTION
Once the action got going, a lot of this sport's troubles receded to the background. Still, the absence of the Russians could not be ignored. It was emblematic of a wide-scale doping crisis that has roots in the upper reaches of the International Association of Athletics Federations.
President Sebastian Coe has taken over the organization, but there are still questions about what he knew, and when, while serving as vice president under Lamine Diack, who is accused of using blackmail to help perpetrate the Russian doping scandal.
The IAAF banned Russia from the Olympics - all but long jumper Darya Klishina, who lived and trained in the United States - and many viewed that as a positive step, and one the International Olympic Committee was unwilling to take regarding the rest of the Russians.
But the depths of the corruption in IAAF and Russia will continue to be exposed after the Olympics end. The IAAF is undergoing changes, including grappling with a proposal to handle drug testing independently. For the sport's sake, this storyline needs to shift well before Tokyo.
The 32 medals the U.S. grabbed pretty much hit the mark that Duffy Mahoney, the chief of sport performance for USA Track and Field, predicted if the Russians didn't show.
The U.S. won gold in three relays. Not bad. Oh, but that fourth one. The men's 4x100 team flamed out again with an illegal pass of the baton. The U.S. is medal-less in that event for the past three Olympics, hasn't won gold since 2000, and it can't all be blamed on the pressures of racing Bolt.
There have been so many studies and working groups and practice plans for this team, and none of them really work.
One suggestion: Find runners who want to make relays their top priority. Take a look at the program in Japan, which captured a silver medal Friday night.
A MODEST PROPOSAL
The final scene of Bolt in action on the track came in the wee hours of Saturday morning. He was throwing a javelin. Think of the possibilities.
Yes, he says his Olympic career is over, but also concedes his coach, Glen Mills, has told him not to rush into retirement.
In the past, Bolt has talked about trying the long jump. More realistic - how about a return to the 400 meters that was once tabbed as his second race, after the 200?
He hates the training, but you could see a little gleam in his eyes after South Africa's Wayde van Niekerk broke Michael Johnson's 17-year-old world record and set the mark at 43.03. Only two guys really ever had a chance to break that, Bolt said: van Niekerk, of course, and himself.
Bolt turned 30 on Sunday. He's got four or five decades of retired life ahead.
What to do?
''I don't know, I don't know,'' he said. ''You just stressed me out.''