When Chelsea's teenage winger Callum Hudson-Odoi first took to the school field as an 11-year-old, he caused quite a stir with one of the coaches, a former player himself.
"Andy Martin, who used to play for Crystal Palace, came running back into the office and said: 'You've got to come and see this lad play football - it's remarkable,'" says former Whitgift School director of sport Alistair Osborne.
The youngster clearly continues to turn heads. Seven years later and after starting only five games for Chelsea, Hudson-Odoi is the subject of a £35m bid from German giants Bayern Munich.
Like Borussia Dortmund, who signed Manchester City winger Jadon Sancho in August 2017, Bayern are hoping that young English players struggling for first-team action in the Premier League will be happy to take a chance overseas.
So can the 18-year-old, an Under-17 World Cup winner and prospectively the most expensive English teenager ever, live up to the hype?
'His name makes me smile' - an early hit at school
"We know what extreme talent looks like and Callum falls into that category," says Osborne, who has also coached Chelsea wing-back Victor Moses and England rugby union centre Danny Cipriani at Whitgift, a fee-paying school in south London which offers bursaries to many of its students.
Hudson-Odoi, who joined Chelsea at the age of eight, made his club debut last January. He has made only 12 appearances since, but recently started successive games for the first time, and manager Maurizio Sarri has said he is starting to reach the "same level" as rivals in his position.
He comes from a footballing family: his father, Bismark Odoi, played for top Ghanaian side Hearts of Oak before becoming his son's agent and older brother Bradley, who was at Fulham's academy and now plays with non-league Wealdstone, also advises him.
Hudson-Odoi helped Whitgift, where he studied from the age of 11 to 14, to two Independent School National titles and still visits the Croydon school to catch up with friends.
"The sky's the limit for him because of his talent but he's a likeable person and great for team morale," Osborne says. "If you say his name to me, it makes me smile.
"But there are other factors which are arguably more important such as his personality and his determination, and a lot of that comes from the support he gets from his parents."
All he wants is a chance to compete' - a dad's wish
"Callum thrives on a challenge," says his father, explaining that he enjoyed playing with older age groups at Whitgift and Chelsea.
As an under-15 player at Chelsea, he was good enough to play in the under-16 team and scored more than 40 goals.
That led to his first taste of international football with England U16s. He scored on his debut and, with support from Chelsea coaches such as Jim Fraser and former England U16 coach Dan Micciche, rose to the challenge in a group that also included Manchester City's Phil Foden and Manchester United's Angel Gomes.
"It's his mission to make it in football," his father says. "All he wants is a fair chance to play, a chance to compete.
"He's always been passionate about the game. When he was younger, there were occasions where I couldn't take him training because of work and he was crying when I got back so I had to take him down the park later to satisfy him. He eats, drinks and sleeps football."
He has won two FA Youth Cups and the Under-18 Premier League title with Chelsea but it was as part of England's U17 World Cup winning team in 2017 that he caught Bayern's eye, providing two assists in the 5-2 win over Spain in the final.
As with Dortmund's Sancho, now a full England international, Hudson-Odoi and his family are said to be single-minded about getting first-team action and know his value.
Championship moves have been offered before, but the preference is to play at one of Europe's elite teams, even if it means permanent departure from a club that has been his home for 11 years.
So how good is he?
As exciting as his progress has been, Hudson-Odoi is not the first talent to emerge from Chelsea's youth ranks and receive rave reviews.
As former Blues winger Pat Nevin tells BBC Sport: "What we're saying now about Callum is exactly what everyone was saying about Dominic Solanke two years ago."
The 21-year-old striker left Chelsea in 2017, and joined Bournemouth for £19m this month after failing to break into the Liverpool team.
The difference with Hudson-Odoi, however, is that the biggest club in German football is knocking at his door.
Nevin thinks this is partly to do with Bundesliga clubs recognising that the World Cup winning England U17 team is one of the best groups of emerging youngsters in football.
"The Bayern offer is extraordinary," the former Scotland international says. "You don't spend that money on a kid if you think there's a chance of failure."
Nevin adds: "There is no doubt he has all the things you want in terms of pace, skills and vision. But more importantly, he has a willingness to learn and an ability to work things out for himself on the pitch.
"He has one cracker of a trick, too, which is unusual. Unlike most players, he doesn't need to touch the ball wide first before striking it with more power, he has this very direct way of shooting with the ball almost straight in front of him."
There is research that suggests young players' brains do not stop developing until they are in their mid-20s, so trying to assess how far an 18-year-old will travel is close to impossible.
And for every Hudson-Odoi, there is a Solanke, or a Carlton Cole - players who don't quite reach their early potential. As former Chelsea left-back Graeme le Saux says: "He still has a huge amount to learn and he'd be the first to admit that."
Nevin adds: "It's not about what he brings to the team now, it's about the potential he brings, and there is plenty there."
Is he better off at Chelsea or Bayern?
The question now is whether that potential is more likely to be fulfilled in west London or Bavaria.
Like Manchester City with Sancho, Chelsea now know what it's like to have a promising youngster demanding first-team football rather being content to pick up a healthy wage in the reserves.
As one of Hudson Odoi's former coaches says, that is no crime. Some might say it is refreshing.
Le Saux says Bayern's £35m bid has "put pressure on Chelsea to demonstrate there is a pathway for Callum - if that can be done, then I would still think he would rather develop at Chelsea."
But consider the established wide players Hudson-Odoi must usurp: Eden Hazard, Willian, Pedro and the £58m Christian Pulisic, who will join from Dortmund next season.
Nevertheless, with Willian now 30 and Pedro 31, Nevin believes a patient approach could pay off for the Englishman.
"You don't get a special brief because you are born in a certain country and, clearly, he's not good enough to walk into Bayern's first team just now because he can't get into Chelsea's," he says.
"But if you think you're good enough to get a game at Chelsea next year, it wouldn't be a bad thing to stay and have a go at that. Right now, he might be dithering [about a decision]. He'll know the answer by next season and that won't be too late."