A £31.4m fee for an 18-year-old with only a season of senior football behind him may seem high-risk from the outside but those who have worked with Charalampos Kostoulas see it differently.
"For me, it's a low-risk decision because I see a lot of potential in him," Sotiris Silaidopoulos tells Sky Sports. And he should know. He coached Kostoulas for four years at Olympiakos, first as boss of their UEFA Youth League-winning U19s, then as a first-team assistant.
Kostoulas' boyhood club are in no doubt that he can become one of the best strikers in Europe. Clearly, it is a view shared by those in charge at Brighton, who have won the race for his signature despite interest from a long list of other clubs.
He becomes the second-most expensive signing in Brighton's history after the £40m Georginio Rutter. The hope now is that he will join a long list of young players to flourish there, including Moises Caicedo, whose sale to Chelsea in 2023 banked the club £115m.
The clamour around their latest addition began to build during Olympiakos' historic UEFA Youth League triumph last year.
Kostoulas was one of the youngest players in their team but finished the tournament with five goals and two assists in eight games, helping them see off heavyweight opponents in Inter, Bayern Munich and AC Milan on their way to lifting the trophy.
Kostoulas, an Olympiakos player since the age of 12, was duly promoted to the first team, scoring seven times in 22 games last season as they won the Greek Super League and also helping them win the domestic cup. He made a further eight appearances during their run to the last 16 of the Europa League.
All the while adapting to a new position.
Kostoulas excelled as a No 9 for the club's academy sides but the presence of top scorer Ayoub El Kaabi at first-team level meant he was used in a second striker role by manager Jose Luis Mendilibar, a key figure in the youngster's development who demonstrated considerable faith in him right from the start of last season.
Kostoulas rewarded that faith and took the positional change in his stride. "That shows how he can adapt and how fast he can understand what the game requires," says Silaidopoulos. "He can play in all positions in the front line."
His versatility is just part of his appeal. Kostoulas has the technical skill to link the play, beat defenders in one-on-ones, create chances and combine with team-mates when coming short or drifting wide. He also boasts the frame and physicality of a far older player.
"His physical capacity for his age is extraordinary," says Silaidopoulos. "He's a guy who is very strong. He can keep the ball like a targetman and change direction very fast using his body.
"His technical ability, especially inside the box, is that of a great finisher. He can score with both feet, with his head. But, for me, what people underestimate a lot in Kostoulas is how clever and how intelligent he is during the games.
"Most people only see the first parts, like the physicality and how good his technique is. His biggest strength, for me, is his intelligence and how fast he can adapt to what a game needs.
"It is amazing for his age."
Kostoulas only turned 18 at the end of May and is expected to make the step up from Greece's U21s to their senior squad soon.
Brighton hope his adaptability and intelligence will help him make a smooth transition to the Premier League. There is further encouragement to be found in his strength of character.
"For me, that is another important aspect of Charalampos, maybe even the biggest one," says Silaidopoulos. "He is super-confident in himself. He doesn't feel pressure. Even as a 17-year-old joining the first-team, he had the feeling that he was in the right place."
Kostoulas was similarly assured when he was promoted to the U19s aged 14, and again when he appeared for the club's B team at 15. In November, he became the youngest player in the club's history to score in the Greek Super League when he headed their opener in a 3-2 win over then-champions PAOK at the age of 17 years, five months and 11 days.
That goal, flicked into the corner of the net after he ghosted in behind the PAOK defence to meet a diagonal cross from team-mate Chiquinho, was an example of his killer instinct in the opposition box.
"That is something you either have or you don't have," says Silaidopoulos. "His feeling inside the box is amazing." For the various coaches tasked with honing his talent in the club's academy, it was just about adding technical details to go with it.
"One of the main aspects we wanted to develop in the academy was the way he took his first touches, especially in tight spaces, to always be in the right direction to finish with only one or two touches inside the opposition box," adds Silaidopoulos.
"There were also other aspects we worked on, like how to move inside the box to free himself from his opponent as a striker. Now, playing in the first team, he has also developed his ability to arrive in the box from the second line, as a second striker."
The first-team staff at Olympiakos were convinced about Kostoulas' capacity to handle the step up to senior level as early as pre-season last summer, when he impressed along with midfielder Christos Mouzakitis, another exciting prospect from their U19s.
Both players went on to feature prominently under Mendilibar, helped by the presence of their U19s coach, who was promoted to the Spaniard's backroom team to aid their transition.
"In my experience, young players often need time to adapt to the dynamic, to the tempo of training at first-team level, maybe six or seven months," says Silaidopoulos.
"But our kids from the academy showed they can do it quicker. They showed how well-educated they are and the character they have built up in our academy. They share the values of the club, being humble, hard working and confident in themselves."
Olympiakos president Evangelos Marinakis, who also owns Nottingham Forest, deserves considerable credit for the talent now coming through the club's youth set-up having invested heavily in their academy and placed it at the heart of his vision for the club.
Their UEFA Youth League success has made them a case study in youth development in Greece but the country's exciting crop of young players includes the 17-year-old Genk midfielder Konstantinos Karetsas in addition to Kostoulas, Mouzakitis and others at Olympiakos and elsewhere.
Brighton spotted the market opportunity in the country early, having already signed 19-year-old forward Stefanos Tzimas, a product of PAOK's academy, from German side Nurnberg in February.
It is Kostoulas, though, who merits the most excitement. The £31.4m fee being paid by Brighton is the highest ever received by a Greek club. There seems little doubt on either side that he is worth it.
"For me, he is a perfect modern striker who can also play in different positions in a really good way," says Silaidopoulos.
"I think Brighton have made a great choice to sign him."
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