Buster Posey scored on a 10th-inning fielding error and the San Francisco Giants edged Cincinnati Reds 2-1 on Tuesday to avoid being swept in their Major League Baseball playoff series. The Reds, who have not won a playoff series since 1995, still lead the best-of-five National League division series 2-1 with game four at Cincinnati. A fifth game if needed would be in Cincinnati on Thursday. Posey led off the 10th inning for the Giants with a single and took second base on a single by Hunter Pence, who limped to first with a sore left calf muscle. Reds relief pitcher Jonathan Broxton struck out Brandon Belt and Xavier Nady but the base runners advanced when Cincinnati catcher Ryan Hanigan failed to catch a throw from Broxton.