Angel Pagan singled in the go-ahead run in the top of the ninth inning as the Giants rallied past the Cubs, 7-5, yesterday at Wrigley Field.  Alfonso Soriano clubbed a three-run homer for the Cubs, who have dropped five of their last seven.  Carlos Marmol fell to 2-and-3 with the loss.  The Northsiders kick off a four-game series with the Washington Nationals in the nation's capital this afternoon.  Jeff Samardzija [[ suh-MARD-juh ]] gets the nod opposite Ross Detwiler in the opener.