An ex-international footballer for Paraguay and former manager of his country's national side at every level from Under-17s to the senior team, Carlos Jara Saguier knows a talented young player when he sees one.
Sergio Diaz was among the best he ever worked with.
“I saw a very complete player with his intelligence and decision making, as well as with his feet”, Jara Saguier says, speaking exclusively to Goal via a translator. "When he was a kid, he was already shining for the Cerro Porteno first team.
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“He was a great team-mate too, and one of his best traits was that he always did what was expected of him - he never overcomplicated things.”
It is fair to say that since Jara Saguier worked with Diaz as a 17-year-old, his career has become rather more complicated.
Nicknamed 'the Paraguayan Aguero' as a teenager, Diaz joined Real Madrid in 2016, but in five years on the books of the Spanish giants he is yet to make an appearance for the first team.
Instead he has found himself travelling around the world, taking in four different loan spells without ever finding the form that saw him twice named to Goal's NXGN list of the top teenage footballers on the planet.
So what happened?
Back in July 2014, Diaz made his top-flight debut for boyhood club Cerro Porteno at just 15, scoring his first professional goal two months later.
His performances, rather unsurprisingly, drew attention from major European clubs, including Liverpool, Manchester United and Real Madrid, while in 2015 he revealed himself as an Arsenal fan, saying that he dreamed of playing for the Gunners in future.
On the international stage, Diaz was the star player for Paraguay at the U17 World Cup in 2015, with Jara Saguier as his coach.
While the tournament was disappointing for the country - Paraguay followed an opening group-stage win over Syria with defeats to France and New Zealand to exit as one of the worst-ranked third-placed sides - the youngster did enough to further attract the attention of top sides.
“When Sergio came to the U17s, he had a big advantage, as he had already been called up to the U20s at 17 years old," Jara Saguier explains. "He was the star, he was our best player.
"We were already aware of the interest from Real Madrid, and other scouts who had come to watch him. It all happened so fast, in a very short time he was already on his way to Madrid.
"I was very happy with how it came about, a lot of players earned transfers on the back of that World Cup.”
After further international recognition at the 2016 edition of the prestigious Toulon Tournament, where Diaz scored in wins over Guinea and Japan despite playing two years below his age-group, Madrid finally swooped for their wonderkid.
His first season in the Spanish capital saw Diaz return five goals in 36 appearances for Castilla, Real’s B team, before he was loaned to Segunda Division side Lugo to further aide his development.
While there, though, he suffered an ACL injury in November 2017 which kept him out of action for 10 months.
As he struggled to regain full match fitness, he was again sent on loan, this time to Brazilian giants Corinthians, who had found themselves embroiled in a shock relegation fight.
In a bid to rebuild the club, the decision was made to build around young talent, and in Diaz they got themselves a player who they knew from first-hand experience could be a difference maker.
"The first time I saw him play live was in 2016, the year he first got nominated for NXGN, he was a youngster for Cerro," Tomas Rosalino, a freelance journalist in Brazil who has covered Corinthians since 2015, tells Goal.
"They played Corinthians in the Copa Libertadores in Asuncion, and basically he destroyed Corinthians. He was clearly the best player on the field. That game was the reason Corinthians brought him to play here two years later.
“There are stereotypes in South American football – the Brazilians who do beautiful skills, the Uruguayans and Argentinians who are more direct. In Paraguay, it is that they just defend. The best forward in their history was Roque Santa Cruz. I cannot remember a Paraguayan who dribbled as well as Sergio Diaz.
“In that game, he came on at half-time and he demanded the ball all the time. I remember [then-Corinthians manager and now-Brazil boss] Tite raving about him after the game.
"From that day Corinthians followed him. When the opportunity came to have him, they didn’t even think. He has a knee injury? No problem.”
There was, however, a problem.
Diaz had not played for six months by the time he arrived at Corinthians in July 2018, and he could not even get onto the field until September of that year.
When he eventually appeared, it would be one of only four outings before he began to suffer from tendonitis in his knee. The gamble by Corinthians had not paid off, but it was not just physically where Diaz was beginning to struggle, with his confidence understanably shot to pieces.
“He came into the mixed zone [after a game], and he was a kid – he didn’t talk that well, he was really shy," Rosalino recalls. "He just said he hoped he could do well at Corinthians.
"He spoke about the pain in his knee, how it meant he sometimes missed training, how the next couple of days after training would be rough for him.
“It was such a shame, he had a work ethic, he was trying, but he could never train for the amount of time Corinthians wanted."
Diaz is now 23, and after a short spell back at Cerro, most notable for him getting into hot water after breaking coronavirus lockdown rules, his most recent loan has been with Liga MX outfit Club America, where he has played a bit part role; only eight games, and not a single minute during the 2021 Clausura as his side chase the league title.
And so while he continues to have a player profile tab on Real Madrid's website - one which describes him as an "attacking footballer with great ball control; a powerful, fast striker, very skilful with the ball at his feet who can find the back of the net with relative ease" - the chances of him ever representing them continue to diminish.
"He went a little too young," Jara Saguier admits. "He had very little experience of first-team football, as well as the U20 and U17 commitments which were almost like a full-time job, so he had very little time to prepare.
"He went from an atmosphere where he was the big star, the golden boy, to Madrid where he was just another player. He had to fight on his own, a long way from home, and that was obviously very difficult.
“The injury definitely hurt his chances of establishing himself in Spain. Once you come back, you don’t know if you will be the same player. I’ve lost track of him a little, since he went to Spain.”
Rosalino agrees: "Real Madrid should be the final stage for a footballer. He had one good season in Copa Libertadores, where Cerro got to the knockout stages; it was way to early for him to go to that level.
"If he had stayed in South America, he would have had a lot more competitive games, and become a better footballer."
And what happens next?
“He’s 23 now, which is still young, he can have a good career," Rosalino continues. "But it is a hard thing to do psychologically – people said he was the future of Paraguay. It is really hard for a guy who hits such high standards so early in his career to understand he won’t be that again.
“He was a phenomenon in Paraguay, but I don’t think he can reach that level, or play for Real Madrid again. He could play in a competitive league in Europe, he’s in Mexico which is a good league. He could come to Brazil, play a full season of 50-60 matches."
Jara Seguier, meanwhile, believes there is still hope for the player who enchanted him six years ago.
“Whether he plays depends on him, it is up to every player to make their case. He was born a star, but what he needs to do now is slow down, decide where he wants to go. He needs to focus on his own game and the next steps.
"He is a great player, and he will get over this difficult time.”
Translations provided by Daniel Edwards