The Detroit Lions rivalry began in the 1950s, when the Browns and Lions played each other in four NFL championships. The Lions won three of those championships, while the Browns won one. This was arguably one of the NFL's best rivalries in the 1950s. Since the NFL-AFL merger of 1970, the teams have met much less frequently with the Browns' move to the AFC. From 2002 to 2014, the two teams played an annual preseason game known as the "Great Lakes Classic".