San Francisco, CA (Sports Network) - Mike Cameron slugged a three-run homer and Darnell McDonald hit a solo shot as Boston doubled up San Francisco, 4-2, in the second installment of a three-game interleague series.
Starter Clay Buchholz lasted just one scoreless inning before leaving with a hyperextended left knee suffered on the basepaths, paving the way for Scott Atchison (1-1) to pick up the win by allowing one run over 2 1/3 relief frames.
In his season debut, Madison Bumgarner (0-1) was charged in the setback with five hits and four runs with five strikeouts over seven innings.
McDonald's solo homer in the first put the Sox ahead, then the visitors added three more in the second.
Beltre hit a leadoff single and Bill Hall walked with one out before Cameron launched a three-run shot to dead center.
The Giants picked up single runs in the fourth and sixth thanks to Posey, who grounded into a run-scoring fielder's choice in the former and lofted a sacrifice fly in the latter.
Jonathan Papelbon then earned his 17th save by retiring the side in order in the ninth.
The Red Sox have won four of the last five meetings with the Giants...In a pregame ceremony, the Giants retired Monte Irvin's number 20. The Alabama native played with the club in New York from 1949-55 and was part of the majors' first all-African-American outfield along with Willie Mays...Prior to the game, the Red Sox announced that second baseman Dustin Pedroia will be lost indefinitely after suffering a broken left foot. Pedroia was placed on the 15-day disabled list and shortstop Angel Sanchez was recalled from Triple-A Pawtucket.