Late Saturday at sparsely populated Olympic Stadium, the proceedings on the final night of track and field vacillated between bet-the-ranch certainty and murky ambiguity. Four American women ran four laps as a team, which meant one portion of the night would provide predictability. The rest of it? Well, hardly anybody knew how to interpret the events — or in some cases even what had happened in the first place.

Start with the cleanest part: The U.S. women’s 4x400-meter relay team won its sixth consecutive gold medal, the latest milestone in a dynasty punctuated by Allyson Felix, the anchor, raising the baton above her head as she crossed the line, having left her nearest pursuer so far behind she might as well have been chilling in Ipanema, sipping a caipirinha.

“Just happiness,” said Felix, the most decorated American female track and athlete ever. “When you secure that gold medal, it’s a special moment.”

One night after the U.S. men’s 4x100 relay team suffered disqualification because of a shabby handoff, the 4x400 team — Arman Hall, Tony McQuay, Gil Roberts and anchor LaShawn Merritt, who won his second career gold — matched the women with a gold of its own. File that under the easy portion of the night, too, because American victory became customary this past week. The United States has won 31 track and field medals, the most since 1956, 13 of them gold, their top performance since 1996.

Every U.S. medalist from the Rio Olympics

After that? On the same track sprinted Caster Semenya, whose mere inclusion always will engender a wide spectrum of opinion. When she blows away the field, as she did in the women’s 800 meters, the voices on both sides of a complex debate only grow louder.

And her saga seemed cut-and-dried compared with the loopy aftermath of the men’s 5,000 meters. One American lost a silver via disqualification and another, aged 41 years, leapt from fifth to third place on rulings even he was not sure how to feel about. At least that’s how it stood for about an hour.

Paul Chelimo, a 25-year-old who serves in the U.S. Army, smashed his personal best by more than 15 seconds to cross the line second with a time of 13:30.90, less than a second behind Great Britain’s unimpeachable Mo Farah. Chelimo celebrated the achievement of his life until an NBC reporter informed him, on live television, that he had been disqualified for infringement.

“That was the most heartbreaking thing in my life,” Chilemo said. “It’s really something. I couldn’t even wrap it up in my mind.”

Original fourth-place finisher Mohammed Ahmed of Canada also had been disqualified, which bumped Bernard Lagat, a 41-year-old in his fifth Olympics, from fifth to third and on to the podium.

But about an hour after the disqualifications had been announced, the IAAF reversed the decision and reinstated Chelimo. The initial devastation could be replaced by a medal.

“Thank God they didn’t take my silver medal because I worked out for all my soldiers,” Chelimo said. “We work out together every day. I represent them, and they represent me.”

For Lagat, it turned out the bronze medal was only temporary. But he seemed not to mind, having felt unsatisfied winning on a medal on technicality in the first place.

“It is hard to imagine,” Lagat said. “. . . To me, I feel like, yes, things happen. But then I guess if the rules are like, whatever decision they want to make tonight, I’m good with.”

There was no ambiguity in the women’s relay. The United States won its sixth consecutive gold medal in the event, extending one of the great Olympic dynasties. Courtney Okolo gave the United States an enormous lead after one lap, and Natasha Hastings and Phyllis Francis only extended it before Felix finished the job, crossing in 3:19.06.

“I definitely felt a lot of pressure because I knew these ladies had been here before and I didn’t want to mess it up,” Okolo said.

Felix won her sixth gold medal and ninth overall, adding to both of her American records for a female track athlete. In Rio alone, Felix has won a silver in the 400 meters and golds in the 4x100 and 4x400 relays. At 30, Felix knew she may have run her last Olympic race.

“Definitely,” Felix said. “You never know what the future holds, and I think this year showed me that. I just took it in and embraced it.”

The U.S. women’s 4x400 relay team and Semenya share an ability to produce awe. Beyond that, one entity is a sure thing, and the other person is an enigma. Semenya dominated the 800 meters with a blistering final lap of 57.7 seconds, blowing past silver medalist Francine Niyonsaba in the final 100 and leaving the field in her wake.

When she crossed the finish line, Semenya flexed both biceps and strutted. Her defiant performance surely will renew the debate over her inclusion at the sport’s highest levels. She is believed to have an intersex condition called hyperandrogenism, meaning her body may produce testosterone at far higher levels than a typical woman. Track officials, coaches and runners believe the condition gives Semenya an unfair edge. But if it does, there is little she can do about a natural feature of her body, and in July 2015 the Center for Arbitration in Sport erased rules prohibiting testosterone levels in women.

Semenya, 25, rarely addresses reporters and even more seldom discusses matters pertaining to testosterone levels. The first question she received in her news conference concerned the topic, and she handled it deftly.

“Tonight is all about performance,” Semenya said. “We’re not here to talk about IAAF. We’re not here to talk about speculation. I think tonight is all about performance. I think this press conference is all about the 800 meter that we ran today. So thank you.”

Earlier, an unwitting divisive figure though she may be, Semenya had said she believed sport should unite the world. In her news conference, she elaborated.

“It’s all about loving one another,” she said. “It’s not about discriminating people. It’s not about looking at people how they look, how they speak, how they run. It’s not about being muscular. It’s all about sports. I think when you walk out of your apartment, you think about performing. You do not think about how your opponent looks like. You just want to do better. So I think the advice to everybody is just go out there and have fun.”

On a night when the United States won two relay titles, a high jumper passed a proverbial baton. In her fourth and final Olympics, 32-year-old Chaunte Lowe came to close to winning her first Olympic medal. She finished fourth, unable to clear 1.97 meters (6 feet 5½ inches) until her third try and then missing all her jumps at 2.00 meters (6-6¾ ).

Her best Olympic performance came after a touching show of compassion. Vashti Cunningham, the 18-year-old daughter of former NFL quarterback Randall, fell from the competition when she failed three times to clear 1.93 meters (6-4), well below her 1.99-meter personal best. A fiery competitor, she took no immediate solace in making her first Olympics or the promising future ahead. Asked what lesson she would take from her first Games, Cunningham replied, “Not to lose.”

After Cunningham knocked over the bar for the final time, she cried while walking back to the warmup area. Lowe, the American high jumper Cunningham most reveres and studies closest, scurried toward her and embraced. Lowe, who was still in the competition, told her, “You had a great season, and you’re an amazing jumper.”

“You know the heartbreak she’s feeling,” Lowe said. “From my perspective, I see that she’s 18 and has probably another 18 years ahead of her in competition. But to her, this is her world. For her, she feels like it’s a failure. From my point of view, I see the future of high jump.”