In Italy, there are only three teams to have retired their number 10: Brescia, who fell madly in love with Roberto Baggio in just four years there; Avellino, who also named their stadium after their star Adriano Lombardi just as Napoli - the third case of retiring the number - did with Diego Armando Maradona.
Unofficially, however, there is another club where it is no longer appropriate to wear the number 10. That is, of course, at Roma. They will struggle to find a player who will have the courage to wear the same number as the legendary Francesco Totti.
Proof of this is that Paulo Dybala (29), despite having had the reception as an absolute champion at the Colosseum square, preferred to opt for the number 21 for his time in Rome.
It is not an easy decision to put the most important and iconic number away in a drawer forever. Those clubs who have done this have because they are sure that there will never be anyone else equal to their heroes, both on and off the field.
Barcelona's experience, when they handed Lionel Messi's (35) number 10 to Ansu Fati (20), is a good example of how it is not enough to just be the epitome of the number stylistically on the pitch to deserve the honour of wearing it. That's partly because, in a footballing respect, they are very unlikely to see a stronger player than Messi ever again at Camp Nou.
On Sunday evening, in our Top Match of the week, Napoli and Roma will take the field without number 10s. That fact provides further proof that the shadows of Maradona and Totti still loom large over these teams.
In Naples, the decision to retire Maradona's shirt came at the turn of the new millennium, almost 10 years after Maradona's farewell from the club. However, the last one to wear the shirt was actually Mario Bogliacino, in 2006. Although, that year the Azzurri played in Serie C and the regulation imposed that they must use numbers 1 to 11.
Gianfranco Zola inherited the iconic shirt from Diego although another Argentine is the second most legendary number 10 in the history of the club: Omar Sivori.
The transfer from Juventus of Sivori - one of the so-called Angels with dirty faces from the Argentine national team - undoubtedly represents one of the most important moments in the history of the Neapolitan club, as Mimmo Carratelli assures in his book The great history of Naples when he recalls that the president Achille Lauro bought two naval engines and paid 70 million lire for him.
In the capital, the other great Giallorossi number 10 was Giuseppe Giannini. The so-called Prince wore his team's shirt for 15 years, quickly becoming its symbol.
Beloved by his fans - second, in this respect, only to Totti and, perhaps, to Agostino Di Bartolomei - Giannini scored just 49 league goals for Roma but only because he was an atypical 10 who preferred to play all over the pitch rather than just in the final third.
There may be no literal number 10 on display in the Derby del Sole this weekend but it is sure to be a fantastic match regardless as two of the heavyweights of Italian football go head-to-head.
