Every September, shortly after most of the domestic football seasons in Europe have begun, Uefa, the continent's governing body, organise a seminar for what it calls the elite club coaches.
They take advantage of a break in the calendar for international matches to bring together the best managers for a two-day seminar. The attendance is always very high; few turn down the chance to compare notes and lobby the organisers of the Champions League for changes they would like to see introduced.
At the end of the talks, which are mostly informal, think-tank style discussions, the coaches gather for a team-group photo. It is diverting to see who sits near whom, to wonder if the public froideur that has at times chilled the relationship between, say, Arsene Wenger and Sir Alex Ferguson, means they keep a distance from one another, or how close Jose Mourinho perches to Claudio Ranieri, or Jesualdo Ferreira, or Gigi Del Neri or any other of the fellow professionals he regularly sneers at through the media.
This year's photo from Nyon, the Swiss city where Uefa has its headquarters, should be particularly striking, not because of background rivalries behind the smiles, but because there will be fewer grey hairs, fewer wrinkles on the assembled faces. The archetype of the successful club coach in Europe is changing rapidly.
Take Rudi Garcia, whose Lille team can confirm the French league title tonight if they draw or win at Paris-Saint Germain, the team they defeated last Saturday in the French Cup final.
Four years ago, Garcia was working in the French second division. He was then 43 years old, and was preparing to bring to an end his spell as head coach of Dijon. His reputation as an imaginative, dedicated instructor was growing, but only so far as it interested unglamorous Le Mans, who took him on in Ligue 1.
Garcia had not had an illustrious playing career to usher him into management at an upper rung of the ladder, though he had been a popular player at Lille in the 1980s, so supporters remembered him well when he took charge of the northern club three years ago. They serenade him now. Lille have two championnat matches to earn the point they need for a first league title since 1954. "We're 93 per cent there," says Garcia, with studied precision.
Three years ago, Massimiliano Allegri could scarcely have imagined a taking a seat at the Uefa elite coaches convention. He was invited for the first time last year, because the AC Milan he had just taken on, at the tender age of 42, were among the teams in the Champions League, as usual.
Thanks to Allegri, they will go into the next European Cup as Serie A title holders. Milan's has not been as long a wait as little Lille's, but the seven years between their previous scudetto and the 2010/11 prize seemed a long gap to milanisti. Allegri's next challenge is to return Milan to the level, in Europe, that made them the most regular Champions League finalists of the past 20 years.
Allegri's new neighbour, the coach of Inter Milan, Leonardo, is even younger than he is. The Brazilian is 41. Pep Guardiola, who will lead the Spanish champions Barcelona into his second Champions League final in three years next weekend, is 40.
His startling success in the three years since he moved up from coaching Barca B in the Spanish third division is a model for young coaches across the continent, and for presidents and chairman who increasingly opt for youth.
"Pep Guardiola is an inspiration to me for his methodology and the fantastic way his team play," said Andre Villas-Boas, Porto's head coach, after winning the Europa League on Wednesday. Villas-Boas will be the youngest among the new kids on the coaching block in next season's Champions League. He is a mere 33.
Nor is he alone for citing Barcelona, winners of the last three Spanish Primera Liga crowns, as exemplary. A 4-3-3 formation, engraved in the Barcelona manual since the 1990s, has now become the fashionable norm among successful European teams.
German audiences have readily compared the young Borussia Dortmund side with Barcelona, for the vigorous pressing game designed by head coach Jurgen Klopp.
Klopp is not a regular either at the elite coaches' gathering. He is 43 years old, and three years ago was operating in Bundesliga II, the second tier of German football.
Klopp will be the man with the longish blond locks in the photograph released by Uefa in September. And the Real Madrid coach, Mourinho, will be the one with grey flecks in his hair. At 48, Mourinho counts as one of the veterans.