[...] yet when Jeremy Affeldt took the mound to begin the eighth inning Thursday, he felt a few butterflies. "After you've been dealing with injuries, in the back of your mind, you just wonder if everything's going to feel the same," said catcher Buster Posey, who knows a thing or two about coming back from an injury. [...] he retired his final five hitters, including getting Scott Van Slyke to bounce into a 1-6-5-4 double play that erased Gonzalez at third. The Dodgers' Hyun-Jin Ryu (3-1) limited the Giants to four hits in seven scoreless innings. On April 4, San Francisco got to Ryu for eight runs (six earned) in two innings in an 8-4 win in the Dodgers' home opener. Beginning with their division-clinching victory on the final day of the 2010 season, the Giants have won 36 of their past 56 games against San Diego. Steve Kroner is a San Francisco Chronicle staff writer.