The Celtics-Sixers rivalry is a rivalry between two teams of the National Basketball Association, the Boston Celtics and the Philadelphia 76ers, that dates back to the 1950s. The rivalry continues to this day every time the teams play in the regular season and in the NBA Playoffs, usually with a trip to the NBA Finals on the line. It is considered by some to be the second greatest rivalry in the NBA next to the Lakers-Celtics rivalry. Cross sports wise it has been compared to that of the Yankees-Red Sox rivalry with ironically the Boston team taking the spot of the Yankees in this case.