Nate Schierholtz had three hits and drove in a run and Pablo Sandoval doubled leading off the fifth to extend his hitting streak to start the season to 11 games.
Bumgarner (2-1), pitching a day after receiving a new $35.56 million, six-year contract, outpitched Joe Blanton (1-2) and gave San Francisco a shot at a third straight series victory.
The finale Wednesday night for an expected sellout at AT&T Park is another highly anticipated pitching matchup: San Francisco's Matt Cain and Phillies ace Cliff Lee.
Hunter Pence hit a solo home run into the left-field bleachers leading off the fourth for the Phillies—a clout that didn't come close to traveling as far as the one he clobbered in batting practice that cleared the top railing in left and reached the concourse and base of the humongous Coke bottle.
Buster Posey had three hits for the second straight day and also checked off another milestone in his return from last year's season-ending left leg and ankle injury from a collision at the plate with the Marlins' Scott Cousins. Posey had back-to-back three-hit games for the first time since May 29-30, 2010, against Arizona during his NL Rookie of the Year season.
Posey stole his first base in the fifth on a close play at third in which he appeared to get his left hand under Placido Polanco's glove and touch the bag before the tag was placed. Polanco argued and manager Charlie Manuel came out as well but replays showed Posey safe.
Bumgarner allowed seven hits and two runs in six-plus innings, struck out two and walked one. Then, the Giants' bullpen did the rest,—a nice boost considering bearded closer Brian Wilson is expected to undergo elbow ligament surgery and miss the season. Clay Hensley and
Angel Pagan led off the first with a single, then Cabrera tripled to end an 0-for-12 stretch and the ball stopped under the bullpen bench in the deepest corner of right field. Sandoval's RBI groundout brought home Cabrera for a 2-0 lead. Posey followed with a bloop single to center. Pagan hit his third triple of the year in the second.
The Giants missed a chance to add on when Brandon Crawford struck out with the bases loaded in the seventh. He was the lone San Francisco position player without a hit.
The typically sure-handed Giants shortstop also committed a fielding error
But Jimmy Rollins grounded into a double play and Bumgarner retired Pence on a high popup to first baseman Aubrey Huff just behind the mound to escape unscathed. Carlos Ruiz had a sacrifice fly in the sixth for Philadelphia's second run.
Before the game, Manuel had a message for San Francisco's fans: Don't freak out about The Freak's latest funk. Two-time NL Cy Young Award winner Tim Lincecum is 0-2 with a 10.54 ERA after three rough starts so far.
"If they panic and they don't want him they can always send him over here," Manuel said with a grin. "Matter of fact, I'll walk over and shorten the way over here. I might pick him up and carry him. We'll give 'em what they want."
And where might Lincecum fit in the rotation?
"I'll find a way," the skipper said, chuckling.
Notes: Wilson on Wednesday is set to be examined by Dr. James Andrews, who performed his first Tommy John surgery while he was in college at LSU in 2003. ... Former Giants and Phillies outfielder Pat Burrell threw out the ceremonial first pitch. He is now scouting for San Francisco, but will sign a one-day minor league deal with Philadelphia next month to retire with the Phillies. ... Injured Giants 2B Freddy Sanchez, still working back after offseason right shoulder surgery, is set to resume throwing Wednesday after he complained of soreness from playing in an extended spring training game Monday in Arizona. ... Crawford has five errors.