The goalkeeper is the only required position of a team. If they are injured or sent off, a substitute goalkeeper has to take their place, otherwise an outfield player must take the ejected keeper's place in goal. In order to replace a goalkeeper who is sent off, a team usually substitutes an outfield player for the backup keeper (thus effectively the red card and substitution takes out two of the starting eleven players). They then play the remainder of the match with nine outfield players. If a team does not have a substitute goalkeeper, or they have already used all of their permitted substitutions for the match, an outfield player has to take the dismissed goalkeeper's place and wear the goalkeeper shirt.