Giants 3, Cubs 2: Ryan Vogelsong pitched seven strong innings and host San Francisco rallied from an early deficit to complete a four-game sweep of struggling Chicago.

Vogelsong (4-2) scattered eight hits while striking out three without a walk. He fell into an early 2-0 hole in the second inning but quickly settled down, allowing just one runner past first base the rest of the way.

Jeremy Affeldt struck out two of the three hitters he faced in the eighth inning, then tossed a perfect ninth for his first save of the year.

The Giants pushed the winning run across in the seventh when Buster Posey led off with a walk against Carlos Marmol (0-2), moved to second on an Angel Pagan base hit, took third on a walk to Brandon Belt and scored when Joaquin Arias grounded into a double play

Brandon Crawford drove in the first two runs for San Francisco, doubling home Belt in the bottom of the second and adding an RBI fielder’s choice in the fifth.

Chicago starter Jeff Samardzija gave up two runs on seven hits in five innings, striking out six but allowing five walks. He and Steve Clevenger each delivered an RBI single in the second inning for the Cubs.

GAME NOTEBOOK: San Francisco won despite going just 1-for-14 with runners in scoring position. ... Posey walked four times, the first Giants catcher to do so since 1975. ... Chicago's Adrian Cardenas had a pinch-hit double to become the first Cubs player since 1957 to open his career with five extra-base hits.