During an international break in 2025, Leganes were preparing to face Real Madrid at the Santiago Bernabeu when an unknown 18-year-old winger from Ivory Coast, who had arrived injured to join the club’s reserve side in January, was unexpectedly handed his senior debut.

Former Leganes manager Borja Jimenez, now in charge of Al Ahli in Qatar, has recalled the moment he first realised the teenager’s potential.

“The first time I heard about Yan was when Jeff Luhnow, the owner of Leganes, showed me a homemade YouTube video of him,” Jimenez said.

“He was 16 years old and playing in one of the club’s academies in the United States. Jeff said to me: ‘We have the new Messi.’ I was amazed by what I saw.”

Jimenez’s first in-person look at Diomande came during a training match against the reserve team in the build-up to the Bernabeu trip.

“I hadn’t seen him properly before,” he explained.

“In his first action he beat a defender with ease. Then he did it again. Next he raced onto a through ball with an incredible first touch. Then he cut inside and fired into the top corner.

“After five or six moments like that, I called the reserve-team coach and told him: ‘Take Yan off now because the next challenge is going to be a bad tackle. Tomorrow he’s training with us.’”

First impressions catch the eye

Diomande only played 45 minutes that day as he was still recovering from injury, but Jimenez believed it was enough.

“He was so much better than first-team players that it was starting to create tension. I didn’t want anyone to kick him.”

Before Diomande joined first-team training, Jimenez offered him some advice.

“I didn’t need to tell him how to play football. I spoke to him about behaviour,” he said.

“I told him to keep doing exactly what he’d been doing, but to respect the senior players. Arrive first, leave last, help your team-mates and understand you’re the new player.

“It was his first experience with a senior squad and I wanted to guide him. He understood everything immediately.”

The winger also quickly impressed his new team-mates.

“We were walking back to the dressing room after training when Dani Raba came over and simply said: ‘This boy is good.’ I just smiled and agreed.”

A debut against Real Madrid

Diomande was immediately included in the squad to face Real Madrid.

“We had to try and win that match, and from the first moment we knew he was different,” Jimenez said.

“His first real action was a burst past Fede Valverde that ended with what we believed should have been a penalty. From that moment, Yan’s story wrote itself.”

Despite only spending around six weeks with Leganes’ first team, Diomande made a major impact.

“He was never intimidated, not even at the Bernabeu,” Jimenez added.

“If he’d arrived in January instead of later, I honestly believe we would have qualified for the Conference League instead of being relegated.

“He transformed us. He scored goals, created chances and completely changed the team.”

Value on the rise

Jimenez also revealed he always expected Diomande’s value to skyrocket.

“When clubs from abroad asked about him, some thought £17m was too expensive.

“I told them that within a year he would be worth two or three times that.”

Leipzig eventually signed Diomande for around £17m, and after just one outstanding season in Germany, the teenager is now valued between £87m and £104m, with his move to Madrid set to be completed in the coming days.