“What I can say is that in his last moments on the pitch playing football, he hadn’t lost anything. It was a pleasure to see him touch the ball. At the moment he accelerates, you can see Messi, you can see Neymar, you can see Mbappe.

“Ooof.”

Alexandre Monnier, a former reserve coach at Paris FC talking about Yann Gueho

At her home in Maisons-Alfort, on a quiet road in the south-eastern suburbs of Paris, Anne-Marie Gueho sighs as she looks up from the dining table where we have been talking for the past two hours.

“I always told him, ‘You have got a gift. You have to do something with it,’” she says.

There is a mixture of sadness and frustration in her voice. Regret, too, at a terrible waste of talent.

“For me, it’s a catastrophe,” Anne-Marie says, shaking her head.

She is talking about Yann, the third of her six children and a boy — now a man — who signed for Chelsea as a teenager and had the potential to become one of the best footballers in the world. 

“When we talk with other coaches about this or that player, we can say, ‘He can become a pro’,” explains Marc Leclerc, who coached Yann at Paris FC, the Ligue 2 club where he played before joining Chelsea. “With Yann, we said to ourselves, ‘At what age will he win the Ballon d’Or?’”

“Every person that played with Yann thinks he could have won the Ballon d’Or — if he was serious,” adds Khallil Lambin, who grew up in the same neighbourhood as Yann and was at Nantes with him. “This boy… it’s the biggest loss in football I’ve ever seen.”

Yann Gueho’s story is extraordinary and has taken months to piece together. Trawl the internet and he almost ceases to exist, like some sort of footballing ghost. Yet mention his name to those who played with him, or coached him, and the responses are remarkable.

“I didn’t know him before he joined Nantes,” Valentin Rongier, the Marseille captain, tells The Athletic. “I’d only heard of him through players at Nantes that came from Paris — they were saying that he is a phenomenon.