SAN FRANCISCO (AP) -- The guy who made the Giants by surprise came up with a most surprising home run against a pitcher who rarely surrenders them.
Steve Holm entered the game as a defensive replacement at catcher, then delivered the biggest hit of the day. His mom, Bobbie, was in the stands to see it, too.
Holm hit a go-ahead, two-run shot in the seventh inning for his first major league homer, and the San Francisco Giants held on for a 4-3 victory in the rubber game against the Philadelphia Phillies on Sunday.
"What I got was a fastball a little up. You're just going to try to be as aggressive as you can be when you come off the bench," said Holm, who emerged as San Francisco's backup catcher after Eliezer Alfonzo and Guillermo Rodriguez both struggled during spring training.
"I didn't know it was out until I hit second. I just kind of cruised in. You make sure you don't fall down or do anything stupid."
Holm homered in his first at-bat on the first pitch he saw from J.C. Romero (3-1) after replacing Bengie Molina in the top of the seventh, sending the ball into the seats in left-center. Romero had allowed only one homer in his previous 61 appearances and came in with an 0.63 ERA over his first 17 outings of 2008.
Holm -- who was greeted in the clubhouse with a couple of celebratory shaving cream pies to the face -- traded away a bat and helmet for the keepsake home run ball, which he planned to present to his mother.
"We'll see how good a mother she's been on Mother's Day," he said with a smile. "No, I'll probably give it to her."
Jack Taschner (2-0) pitched the seventh for the win, Tyler Walker worked a 1-2-3 eighth and Brian Wilson finished for his 11th save in 13 opportunities. San Francisco rallied for its first series win this month in three chances.
The Phillies went ahead 3-2 in the fifth when Pat Burrell hit a sacrifice fly after Ryan Howard's first triple of the year. Howard's hit drove in a run and chased San Francisco starter Jonathan Sanchez.
Phillies starter Adam Eaton drew a bases-loaded walk in the fourth to tie it at 1.
"We definitely are not hitting the ball," Phillies manager Charlie Manuel said. "We've got to hit better than we've been doing to win."
The Giants snapped a season-long five-game losing streak with an 8-2 victory Saturday, then managed just enough offense Sunday. San Francisco hadn't won a series since beating the Rockies two out of three at home to end April, including dropping two of three in Philadelphia from May 2-4.
Reigning NL MVP Jimmy Rollins went 0-for-5 in his third game back from a disabled list stint with a sprained left ankle. He had three hits Friday in his return, missing the cycle by a triple.
The Bay Area native from nearby Alameda used a pink bat with his mom's name on it -- Gigi -- for Mother's Day and breast cancer awareness. She was once a standout middle infielder for the Allen Temple Baptist Church women's fast-pitch softball team in Oakland.
"My mom never made outs," Rollins said before the game.
Afterward, he retired the special bat.
"He said they didn't have any hits in them," Gigi Rollins said.
San Francisco's Ray Durham struck out as a pinch hitter to leave the bases loaded in the sixth, and the Giants missed several other scoring opportunities.
John Bowker singled in a run in the second to give San Francisco a 1-0 lead, but Jose Castillo followed by grounding into an inning-ending double play. The Giants hit into double plays again in the third, fourth and sixth innings -- Castillo doing so in the fourth and sixth.
Omar Vizquel was intentionally walked three times in the eighth hole to bring up the pitcher, but Durham pinch-hit in the sixth. That's after Vizquel got three hits in his season debut Saturday, when he returned following Feb. 27 arthroscopic surgery on his left knee.
The intentional free passes were the most by a Giant since indicted home run king Barry Bonds drew four against Houston on Sept. 22, 2004.
"I was kidding him that I thought he had 25 on his back," Giants manager Bruce Bochy said in a reference to Bonds' old uniform number.
Bochy doesn't plan to overextend the 41-year-old Vizquel, an 11-time Gold Glove shortstop. Vizquel likely will play three or four games at a time, then get a break for a day or two.
"That would be nice, to give me a little rest," said Vizquel, who typically dislikes days off.
The Phillies began a stretch in which they are scheduled to face four lefty starters in a row. ... Giants RHP Kevin Correia, nursing a strained muscle in his left side, hopes to be throwing off a mound again in about a week. ... Sanchez made his first career start vs. Philadelphia. ... San Francisco 1B Dan Ortmeier celebrated his 27th birthday. Zito turns 30 on Tuesday. ... Seven of the Giants' last 11 games have been decided by one run.