Jordy Mercer broke a fifth-inning tie when he homered for the second day in a row, Francisco Liriano struck out six to win his second straight decision and the Pittsburgh Pirates beat the San Francisco Giants 5-2 on Wednesday for a three-game sweep. Liriano (3-4) allowed four hits while outdueling Tim Hudson (3-5), who also struck out six over seven innings but lost his fourth straight outing against the Pirates. The two pitchers had the first hits of the game after each retired the initial eight batters in order, Liriano with a single in the top of the third and Hudson on a double in the bottom half.