Usain Bolt crossed the Olympic finish line and went through the motions for a ninth and final time. It began at the starting blocks in Beijing eight years ago and ended in front of an adoring crowd in Rio de Janeiro. He posed; he kissed the track; he danced; and he waved the green and yellow flag. All the things track fans had seen before and all the things they'd loved.

For eight years, greatness has been just an accepted part of his routine.

"There you go: I am the greatest," Bolt said Friday night, after anchoring Jamaica's gold medal-winning 4x100 relay team for a third straight Olympics. He said it as though he expected this all along.

His final act was as impressive as the others, coming on a night when the United States' speedy women's 4x100 relay team won its second straight Olympic gold medal in the event and the men's again watched a spot on the podium slip away.

The American men were third across the line, and they circled the track with their giant flags just as the women's team had minutes before, celebrating. That's when they saw on the scoreboard that they had been disqualified for a bad handoff.

"It was the twilight zone," sprinter Justin Gatlin said. "It was a nightmare. You work so hard with your teammates, guys you compete against almost all year long. All that hard work just crumbles."

Fans at Olympic Stadium hardly noticed, as Bolt and Bolt alone was in the spotlight. Friday's win gives him nine career gold medals, tying him with Carl Lewis for the most of any modern track and field athlete. He came to Rio de Janeiro hoping to defend all three of his titles - the 100 meters, the 200 meters and the 4×100-meter relay - which he had won at each of the past two Olympics. None of the races was particularly close. The Jamaicans won Friday night's relay with a time of 37.27 seconds, 0.33 seconds better than second-place Japan.

Running the anchor, Bolt again carried his team over the line, and the Americans again were left helpless. Every four years, the U.S. squad proves to be snake-bit: a disqualification in 2008, a stripped silver in 2012 after Tyson Gay's doping violation. This time, the Americans were disqualified for an illegal exchange outside the zone between Mike Rodgers and Gatlin. Canada (37.64) was elevated to the bronze medal.

The botched handoff marked the ninth time since 1995 that the U.S. men were disqualified or failed to successfully get the baton around at an Olympics or world championships.

"It has to be the worst luck for this country ever," Gay said. "It's always something weird, stupid. Simple mistakes always cost us."

The women's team again fared much better. Even though they were running from lane one, the U.S. women's 4x100 foursome had a much smoother trip around the track, defending their Olympic title with a time of 41.01 seconds, a full 0.35 seconds ahead of the second-place Jamaican squad.

Felix became the first woman to win five track and field gold medals, and she'll have a chance to add one more with the 4x400 relay squad that takes the track Saturday night

"Sometimes adversity makes you strong. We each have had a rocky road, kind of a different journey, a unique experience," said Felix, who has eight medals total in her four Olympic appearances. "We just came together. We wanted to keep going."

The American women almost didn't make the finals. In the first round, they had a bad handoff from Felix to English Gardner. But race officials ruled that a Brazilian runner impeded Felix, and the U.S. team was allowed to run an unprecedented time trial later Thursday evening on an empty track at Olympic Stadium to earn a spot in the final. The Americans had no problem with that, posting a time faster than any other relay team in the first round.

While the United States enters the final full day of the track and field competition having won 27 medals at Olympic Stadium - including 10 golds - no one has had a tougher trip to Rio de Janeiro than pole vaulter Jenn Suhr. The defending Olympic and world champion had been sick for most of her time in Brazil, a respiratory infection that saw her vomiting blood Friday morning. She still made it Olympic Stadium for Friday night for the women's pole vault competition but was clearly hampered.

In her third Olympic appearance - Suhr also won silver at the Beijing Games - Suhr managed to clear 15 feet, 1 inch on her second attempt. But she missed all three tries at 15 feet, 5 inches, ruining her Olympic title defense.

Her American teammate Sandi Morris managed to pick up the silver medal. Morris and Greece's Ekaterini Stefanidi both successfully cleared 4.85 meters, but Stefanidi was awarded the gold medal because she had fewer misses on the evening.

"I told myself if I was able to get any medal today, I would just be extremely happy, and I am," said Morris, the 24-year-old American record-holder. "I'm so, so happy and so blessed."

In the women's 5,000-meter race, Kenya's Vivian Cheruiyot set a new Olympic record, finishing in 14:26.18 and chasing down favorite Almaz Ayana of Ethiopia late. Ayana, who shattered the world record in the 10,000 one week earlier, helped set the fast pace but had to settle for bronze. American Shelby Houlihan finished 11th with a time of 15:08.89.

New Zealand's Nikki Hamblin finished last in the race, 1:48 behind Cheruiyot. Hamblin was one of two runners who crashed in the first round heat, sacrificing any shot at a medal by helping each other up and continue in the race. They were both given automatic spots in the final, but the United States' Abbey D'Agostino tore an anterior cruciate ligament in the crash and was unable to race Friday.

In the 4x400 first round heats, both Americans squads advanced relatively easily. The women's squad, which featured Courtney Okolo, Taylor Ellis-Watson, Francena McCorory and Phyllis Francis in the first round, has claimed the gold in the relay at every Olympics since the 1996 Atlanta Games. The group posted a time of 3:21.42, the best of any team Friday night.

The men's 4x400 team, a second-place finisher four years ago, advanced to the finals, finishing second in its heat with a time of 2:58.38, which was 0.09 seconds behind the Jamaican squad.

The night's main event, though was Bolt's Olympic farewell. Even he couldn't envision nine gold medals when he first toed the starting line as a 17-year old at the Athens Games.

"All I wanted to do was run the 200 meters and win Olympic gold medal once," he said.

He'll be only 33 when the Tokyo Games take place four years from now, but promises he won't stick around for 2020 or entertain second thoughts.

"When I retire, that will be it," he said.