Mariano Rivera (born November 29, 1969) is a Panamanian professional baseball player who has spent his entire Major League Baseball (MLB) career with the New York Yankees. Nicknamed "Mo", the right-handed Rivera has served as a relief pitcher for most of his career. His presence in the late innings of games to record the final outs has played an instrumental role in the Yankees' success, particularly the team's late 1990s dynasty, which won four World Series championships.