One moment, it falls and robs you of an Olympic gold medal.
On Friday, it stayed up and Sandi Morris joined the very exclusive 5-meter pole vaulting club.
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In the highlight of the Van Damme Memorial meeting, it came to the last woman standing, and the bar at a height only Russian great Yelena Isinbayeva and American Jenny Suhr had reached.
With 40,000 fans at the King Baudouin Stadium cheering, grit, speed and agility only got Morris this far up – she touched the bar, again, and thought that just like at the Rio Games, it would fall and leave her crestfallen once more.
''I brushed it and I hit the mat and I just thought it was going to fall,'' she said. Instead though, ''the crowd went wild and I looked up and it was still there.''
With her new U.S. outdoor mark, and an age of 24, Morris made clear she is the future of women's pole vaulting.
If only she had an Olympic title to go with it. At the Rio Games, though, Morris had a brush with the bar just as close and if it would have stayed up, it would have been gold. Instead, the Olympic title went to Greece's Katerina Stefanidi, the Greek she beat on Friday.
To cap the memorable night, Morris tried three times at 5.07 meters to break Isinbayeva's world record, the Russian she had idolized during her youth. She fell short. But she has plenty of time to try again.
''It is a good thing that I didn't break the world record tonight since I have next year to go for,'' Morris said. ''If you automatically achieve all your goals right off the bat, what will you have to go for? It gives me a lot of motivation for next season.''
In earlier action, Elaine Thompson extended her sprinting dominance through her last race of the season, with the double Olympic champion beating rival Dafne Schippers in the 100 meters.
In a battle between the two dominant sprinters of the past two seasons, it was no contest.
The Jamaican shot out of the blocks and never let Schippers close to finish in 10.72 seconds. It was her third-best time of the season but still better than any other woman this year.
''Now I can finally go back home,'' Thompson said after her intense season. ''If I have to summarize it in one word: Wonderful.''
Schippers, who complained of sore hamstrings, finished well behind in 10.97. After her habitual slow start she never came close to closing the gap on Thompson.
The Jamaican won the 100 and 200 at the Rio Games while Schippers finished 5th in the 100 and was runner-up in the 200.
Besides Morris, the biggest cheer of the night at the King Baudouin was for an eight-year-old achievement.
The Belgian 2008 women's Olympic 4×100 relay team was officially handed its gold medals after crossing the line at the Beijing Games in second place behind Russia.
The team moved up to gold this year after a Russian runner was caught doping in a retest.
In a stirring ceremony before some 40,000 fans, the four runners were finally handed their new medals by former IOC President Jacques Rogge, who was still in office at the Beijing Games.
Kim Gevaert, Elodie Ouedraogo, Hanna Marien and Olivia Borlee were all dressed in fitting golden tops as they received the biggest prize of their careers. Only Borlee is still competing.
In the 400, South Africa's Caster Semenya proved her versatility. She became the 800 Olympic champion in Rio last month, but at the closing Diamond League meeting she won the one-lap race with a stunning kick over the final straight.
With 150 meters to go, Semenya seemed totally out of the race, but she started clawing back one runner after another, and with a dip at the line she set a personal best of 50.40 seconds, to beat Courtney Okolo of the United States by .11 seconds.
Exhausted, Semenya crumpled to the ground, saying the intensity of the 400 was incomparable to the more tactical 800.
''This is a suicide,'' she said. ''It is crazy.''
Still, Semenya showed that a 400-800 double might be possible at next year's London world championships.
Follow Raf Casert on Twitter at http://twitter.com/rcasert