Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Gustavo Adrián Lombardi (born 10 September 1975) is an Argentine retired professional footballer who played for in Argentina for River Plate, in Spain for UD Salamanca and Deportivo Alavés, and in England for Middlesbrough. He also played for the Argentina under-20 side at the 1995 FIFA World Youth Championship, as well as for the full Argentina national side. Within the sport of association football, a defender is an outfield player whose primary role is to prevent the opposition from attacking. There are four types of defender: centre back, sweeper, full back, and wing back. The centre back and the full back positions are essential in most modern formations. The sweeper and wing back roles are more specialized for certain formations.