Question: What position did Sergio Perez Leyva, a Spanish player, play that is the world's most popular sport played by 250 million players in over 200 countries?

full_context: Document 1: Sergio Busquets: Sergio Busquets Burgos (] , ] ; born 16 July 1988) is a Spanish professional footballer who plays as a defensive midfielder for FC Barcelona and the Spain national team.
Document 2: History of association football: Association football, more commonly known as football or soccer, can be traced to as far back as the Medieval period in Britain (medieval football). The modern game of association football originates from the formation of The Football Association in London, England in 1863 based on multiple efforts to standardize the varying forms of the game. This allowed clubs to play each other without dispute and which specifically banned handling of the ball (except by goalkeepers) and hacking during open field play. After the fifth meeting of the association a schism emerged between association football and the rules played by the Rugby school, later to be called rugby football. At the time, football clubs had played by their own, individual codes and game-day rules usually had to be agreed upon before a match could commence. For example, the Sheffield Rules that applied to most matches played in the Sheffield area were a different code. Football has been an Olympic sport ever since the second modern Summer Olympic Games in 1900.
Document 3: Sergio Romero: Sergio Germán Romero (born 22 February 1987) is an Argentine professional footballer who plays as a goalkeeper for English club Manchester United and the Argentina national team.
Document 4: Crab soccer: Crab soccer (American English and Australian English), or crab football (British English), is an informal sport played by two teams. The objective is to kick an inflated ball into a goal to score points. The game is commonly played in Physical education classes. The game can be played with a regular soccer ball, but is often played with a cage ball. At the end of the game, the team with the most points wins. Unlike soccer, players support themselves on their hands and move with their feet, in motions that make them look like crabs, a method known as crab walking. Crab soccer can be played either outdoors or in a gymnasium, and is more commonly thought of as being a sport mostly played by children.
Document 5: Sergio Pelegrín: Sergio Pelegrín López (born 18 April 1979) is a retired Spanish professional footballer who played as a central defender.
Document 6: Sergio Ramos: Sergio Ramos García (] ; born 30 March 1986) is a Spanish professional footballer who plays for and captains both Real Madrid and the Spain national team. Primarily a central defender, he can also play as a right back.
Document 7: American football: American football, referred to as football in the United States and Canada, and also known as "gridiron football" or simply "gridiron", is a sport played by two teams of eleven players on a rectangular field with goalposts at each end. The offense, the team with control of the oval-shaped football, attempts to advance down the field by running with or passing the ball, while the team without control of the ball, the defense, aims to stop their advance and take control of the ball for themselves. The offense must advance at least ten yards in four downs, or plays, or else they turn over the football to the opposing team; if they succeed, they are given a new set of four downs. Points are primarily scored by advancing the ball into the opposing team's end zone for a touchdown or kicking the ball through the opponent's goalposts for a field goal. The team with the most points at the end of a game wins.
Document 8: Sergio Pérez Leyva: Sergio Pérez Leyva (born 15 May 1993) is a Spanish footballer who plays for CD Mirandés as a goalkeeper.
Document 9: Ball (association football): A football, soccer ball, or association football ball is the ball used in the sport of association football. The name of the ball varies according to whether the sport is called "football", "soccer", or "association football". The ball's spherical shape, as well as its size, weight, and material composition, are specified by Law 2 of the Laws of the Game maintained by the International Football Association Board. Additional, more stringent, standards are specified by FIFA and subordinate governing bodies for the balls used in the competitions they sanction.
Document 10: Professionalism in association football: Association football is the world's most popular sport, and is worth US$600 billion worldwide. By the end of the 20th century it was played by over 250 million players in over 200 countries. Around the world, the sport is played at a professional level by professional footballers, and millions of people regularly go to football stadiums to follow their favourite football teams, while billions more watch the sport on television or on the internet. Football has the highest global television audience in sport. The sport had amateur origins and evolved into the modern professional competition.
Document 11: Sergio Díaz (Paraguayan footballer): Sergio Ismael Díaz Velázquez (born 5 March 1998) is a Paraguayan footballer who plays as a forward for Spanish club CD Lugo, on loan from Real Madrid, as well as the Paraguay national under-20 football team and the Paraguay national under-23 football team.
Document 12: David de Gea: David de Gea Quintana (] ; born 7 November 1990) is a Spanish professional footballer who plays as a goalkeeper for English club Manchester United and the Spain national team. He has been hailed as one of the best goalkeepers in the world.
Document 13: Carlos Caballero Pérez: Carlos Caballero Pérez (born 5 October 1984) is a Spanish professional footballer who plays for Córdoba CF as a midfielder.
Document 14: Association football: Association football, more commonly known as football or soccer, is a team sport played between two teams of eleven players with a spherical ball. It is played by 250 million players in over 200 countries and dependencies, making it the world's most popular sport. The game is played on a rectangular field with a goal at each end. The object of the game is to score by getting the ball into the opposing goal.
Document 15: South American nations at the FIFA World Cup: Association football is the most popular sport in nearly every South American country, and 9 members of the South American Football Confederation (CONMEBOL) have competed at the sport's biggest event, the men's FIFA World Cup.
ground_truth: goalkeeper