Buster Posey scored on a 10th-inning fielding error and the San Francisco Giants edged the Cincinnati Reds 2-1 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 on Wednesday. A fifth game if needed would be in Cincinnati on Thursday. The winner will face either Washington or reigning World Series champion St. Louis to determine a berth in the World Series final. San Francisco managed only one hit in nine innings but two singles in the 10th enabled them to produce the deciding run. 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. The Giants\' Joaquin Arias followed with a ground ball to Reds third baseman Scott Rolen which was bobbled by the eight-time Golden Glove Award winner for fielding skills. By the time Rolen made the throw to first base, Arias was safe at first and Posey had scored the go-ahead run for the Giants, who retired the Reds in order in the bottom half of the inning to seal the victory. Cincinnati opened the scoring in the first inning when Zack Cozart walked, advanced to second on a Ryan Ludwick single and scored on a Jay Bruce single. The Giants leveled at 1-1 in the third when Gregor Blanco was hit by a pitch, moved to second when Brandon Crawford walked, took third on a sacrifice bunt by pitcher Ryan Vogelsong and scored on Angel Pagan\'s sacrifice fly out. Vogelsong and four Giants relief pitcher combined to allow the Reds only one more hit over the next nine innings. Cincinnati starting pitcher Homer Bailey, who hurled the Reds\' first no-hitter in 24 years two weeks ago, kept the Giants hitless through the first 5 2/3 innings before Marco Scutaro snapped an 0-for-10 drought with a single to right field. Bailey struck out six Giants batters in a row at one stretch during his superb start and the 26-year-old right-hander finished with 10 strikeouts over seven innings with only one hit allowed. San Francisco did not manage another base hit until Posey and Pence struck in the 10th.