Match fixing, when motivated by gambling, requires contacts (and normally money transfers) between gamblers, players, team officials, and/or referees. These contacts and transfers can sometimes be found, and lead to prosecution by the law or the sports league(s). In contrast, losing for future advantage is internal to the team and very hard to prove. Often, substitutions made by the coach designed to deliberately increase the team's chances of losing (such as having key players sit out, using minimal or phantom injuries as an excuse), rather than ordering the players actually on the field to intentionally underperform, are cited as the main factor in cases where this has been alleged.