The phrase comes from the game of bridge. A rubber match is the third match of a three-match series. Sometimes it is only played since each participant has already won one match, therefore the winner of the third match becomes the rubber winner. For example, if Alice and Bob are playing a match for first place, with Alice serving first. If Alice wins, they will both have 2 points and the match is over. But if Bob wins, they will both have 1 point and the next match between them will determine who goes home with the trophy. In other words, a rubber match is necessary to determine the champion. Bridge players use the word "rubber" because the matches are usually played on a single set of boards used for all the games in a series. When one player wins two matches in a row, the third match is called a "rubber." The term "rubber match" came into common usage during the early days of tennis when there were only two courts and two games had to be played to decide a match. If you lost your first match, you could still win by beating your opponent in the second game of the series. This would happen very often since the second game was often not completed due to darkness falling before it was finished.