A “tiny figure”, they called her. Barefoot, bewildered, booed. Zola Budd, 18, stands on the track, in the white British strip, amid the chaos following the women’s 3,000m race at the 1984 Olympics in Los Angeles. On the grass, her great rival Mary Decker, in the scarlet colours of Team USA, lies convulsed in sobs. Her boyfriend (later husband), British discus thrower Richard Slaney, picks her up and carries her tenderly to face the world’s press. The world champion transformed into a fallen princess, at what should have been her crowning moment.

It was doubly poignant as Decker had been denied the chance of a medal at the 1980 Moscow Olympics thanks to the US boycott. Budd was the South African who, controversially, had joined Team GB – on the grounds that her grandfather was British – since her country wasn’t welcome anywhere during the dark days of apartheid. The press went wild over the rivalry and their contest was a must-see race.

Nobody could have foreseen what was to happen; at the 1600m mark, bunching up at the front of the race, someone spikes Budd. Her leg splays out, and Decker falls, her dreams crashing around her as she tumbles onto the grass and around 92,500 people in the Los Angeles Memorial Coliseum gasp. The world watching on television gasps. The rest of the field runs on past Decker, a prone, wailing figure.

Thirty-two years on and the two women have been reunited for a feature-length documentary, which gets a nationwide cinema release on the day of its TV premiere. From her home in Myrtle Beach, South Carolina, Budd, now 50, explains her reasons for taking part. “The film- makers gave me the assurance it would be fair.” Decker, 58 next week, speaking from her home in Oregon, looks at it another way. “Over the years we have been approached so many times. I got to the point when I thought, ‘I need to make a decision, so it will be done once and for all.’”

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The film looks at the hinterland of both runners; Budd, growing up in rural South Africa, running barefoot across the Orange Free State. Decker in beribboned pigtails, conquering race after race with her effortless, balletic stride. Both preternaturally gifted, both driven.

Decker was the world record holder in the mile, 5,000m and 10,000m. She set 17 world records and was the first woman to run a sub 4.20 mile outdoors. Aged 17, Budd had broken Decker’s 5,000m world record earlier in 1984, but it wasn’t ratified because South Africa was banned from world sport. Subsequently, by now with a British passport, she won the 1500m at the English national championships. The Olympics was their joint destiny.

The image of Decker falling in the 1984 3,000m Olympic final (not a distance nowadays contested) is now one of public ownership. Does Budd ever think about it now? “Yes I do,” she says quietly. “You can’t not. It becomes part of your life.” What does she recall? “A blur. I only knew someone had fallen. When I passed by the spot again, on the next lap, it was then I realised it was Mary. And the crowd started booing. That’s when I gave up,” says Budd. “Everything leading up to it, all the politics, all the hype, and then for Mary to fall! It was like a soap opera, it couldn’t be real. I slowed down deliberately. I didn’t want to be on the medal podium. In a way I stopped running.”

The race was eventually won by Romania’s Maricica Puica. Budd finished seventh. In the post-race press conference a tear-stained, emotional Decker practically accused Budd of tripping her (it’s now acknowledged that she didn’t), and the teenager was immediately caught in a storm of national indignation.

Was she angry at her treatment? “It did make me angry, but not any more,” says Budd. “I still feel angry at people for blaming me for apartheid, and wanting me to take responsibility for that. But I’m not bitter.”

And Decker? “I don’t think about it,” she says. “It’s something that almost happened in a different lifetime. People need to understand that the Olympics are important, but they don’t define your entire career.”

In the closing moments of the film the two women are reunited at the stadium where it all happened. “It was so small and not intimidating any more,” says Budd. “To be there with Mary put a lot of things to rest. Before, it was this huge stadium full of booing people. But meeting Mary normalised everything. It healed both of us.”

The two women even have a slow, easy jog around the grassed-over track together. “Running on the grass with her was easy to do. It was probably good for both of us,” says Budd, now a running coach at Coastal Carolina University and a distinguished long-distance runner, having conquered the famous South African Comrades marathon (56 miles) twice and the Two Oceans Ultra (35 miles) twice. “I can still run. That definitely helps me.”

Sadly, Decker has been burdened with injury and arthritis. She walks her five dogs across her 55-acre farm. She quilts. She gardens. “I can’t run any more,” she says. “I ride an ElliptiGO bike [blending cycling and running]. That’s my outlet and it’s the closest thing to running that isn’t running. I feel as if I was born to run. But I can’t. But I think I have arrived at a good place. I have one child, Zola has three. We have life.”

She knows she and Budd will always be linked. She doesn’t mind. “Do you know that our husbands have the same birthday? May 16."

In that dreadful moment when she was lying weeping on the track, did she realise that her great rival had effectively given up?

“I didn’t know that,” says Decker.

Neither has a single Olympic medal.

The Fall: Decker v Budd is on Sky Atlantic on Friday at 9:00pm

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