The 2010 FIFA World Cup was an international football tournament held in South Africa from 11 June until 11 July 2010. The 32 national teams involved in the tournament were required to register a squad of 23 players; only players in these squads were eligible to take part in the tournament.
Before announcing their final squad for the tournament, teams were required to name a preliminary squad of 30 players by 11 May 2010, 30 days before the start of the tournament. With the exception of those involved in the 2010 UEFA Champions League Final, the players listed in the preliminary squad were then subjected to a mandatory rest period from 17 to 23 May 2010. The preliminary squad would then have to be cut to a final 23 by 1 June 2010 (midnight CET). Replacement of seriously injured players is permitted until 24 hours before the team in question's first World Cup game, though replacement players do not have to be drawn from the preliminary squad.
Players marked (c) were named as captain for their national squad. Number of caps, players' club teams and players' age as of 11 June 2010: the tournament's opening day.
There were only three national squads made up entirely of players from domestic clubs which were England, Italy and Germany. Nigeria was the only team with no players from domestic clubs.
The English, German, and Italian squads were made up entirely of players from the respective countries' domestic leagues. The Nigerian squad was made up entirely of players employed by overseas clubs. Although Russia, Turkey, and Scotland failed to qualify for the finals, their domestic leagues were represented by 14, 14, and 10 players respectively. Altogether, there were 52 national leagues that had players in the tournament.