during his tenure on Italian club
Napoli, exhibited at the San Siro Museum of Milan. The number 10 he wore was retired by Napoli in 2000. This practice, long established in the
major North American sports, is a recent development in football elsewhere, since squad numbers for specific players were not widely used until the 1990s. Before then, it was typical for players in the starting lineup to be issued numbers 1 to 11 by formation/position on a match-by-match basis, and substitutes to be numbered from 12 upwards, meaning a player might wear different numbers during the season if they were to play in different positions for tactical reasons, or simply not be a regular in the starting lineup. In contrast, in the former
American league the
North American Soccer League, players wore permanent numbers since its inception in 1967. Moreover,
Pelé's #10 was retired by the
New York Cosmos during the farewell of the Brazilian star on 1 October 1977, becoming the first number ever retired in association football.
Mexico was a pioneer country in the use of permanent numbers in football; these were adopted in the
Primera División in the 1980s. Retiring a player's shirt number usually occurs after the player has left the team or retired. It honours a player who has meant much to his club, and no other player is permitted to use that number in the future. In some cases, such as those of
Marc-Vivien Foé,
Davide Astori, and
Diogo Jota, numbers have been retired to posthumously honour a player who died while still active. Also, Norwegian club
Fredrikstad retired
Dagfinn Enerly's number following an on-pitch accident that left him
paralysed. In Britain, only
Bobby Moore's,
Jack Lester's, and
Jude Bellingham's shirt numbers have been retired due to great service to the club as opposed to a tragic incident. Although it had not been officially retired,
Gianfranco Zola's No. 25 shirt had not been reissued by
Chelsea since he left the club in 2003 until re-issued to
Moisés Caicedo in 2023. The
Argentina,
Ecuador and
Cameroon national teams have been prevented from retiring the numbers of
Diego Maradona (10),
Christian Benítez (11) and
Marc-Vivien Foé (17), respectively, by
FIFA rules dealing with squad numbers for Finals tournaments; in other competitions, qualifiers or
friendlies, national associations may assign numbers according to criteria of their choosing. Similarly, several clubs have been required to reissue retired numbers for continental club competitions due to squad numbering rules of continental confederations. For example,
CAF and
CONMEBOL have such rules in their club competitions, but
CONCACAF does not. Some South American teams (such as
Universitario de Deportes and
Flamengo, and even Mexican teams invited for the occasions) occasionally had to re-issue their retired numbers for special cases due to CONMEBOL rules, which stated that shirts had to be numbered 1–25/30 in continental club competitions (such as
Copa Libertadores and
Copa Sudamericana, among others), although nowadays clubs are not forced to number their players consecutively. == Retired numbers ==