The 1990 World Series was the championship series of Major League Baseball's (MLB) 1990 season. The 87th edition of the World Series, it was a best-of-seven playoff played between the defending champions and heavily favored American League (AL) champion Oakland Athletics and the National League (NL) champion Cincinnati Reds. The Reds defeated the Athletics in a four-game sweep. It was the fifth four-game sweep by the NL and second by the Reds after they did it in 1976. It was the second consecutive World Series to end in a sweep, after the Athletics themselves did it to the San Francisco Giants in 1989. It is remembered for Billy Hatcher's seven consecutive hits. The sweep extended the Reds' World Series winning streak to nine games, dating back to 1975. This also was the second World Series meeting between the two clubs (Oakland won four games to three in 1972). As of 2020, this remains both teams' most recent appearance in the World Series. Athletics manager Tony La Russa and Reds manager Lou Piniella were old friends and teammates from their Tampa American Legion Post 248 team.