Susac was in a .074 (2-for-27) skid when he connected with Chad Billingsley's 2-2 slider and drove it over the center-field barrier for his third homer of the season. It was a welcome change for Susac, who had seen similar pitches in recent games but could not make meaningful contact.
"I was trying to do too much instead of driving it right back up the middle," said Susac, whose three RBIs matched a personal best.
Susac's clout demonstrated why Giants manager Bruce Bochy doesn't hesitate to switch Buster Posey to first base and install Susac in the lineup.
"He's dangerous," Bochy said. "He can hit lefties and righties. He uses the whole field. He has pop in his bat. It's nice to have somebody backing up Posey who's a threat up there."
Susac's homer completed a four-run outburst that accounted for all of the Giants' scoring. They completed their first three-game sweep over Philadelphia at AT&T Park since Sept. 4-6, 2000, and reclaimed some of the confidence they squandered while losing eight of nine games before this series.
San Francisco remained 4 1/2 games behind first-place Los Angeles in the National League West and forged three games ahead of Arizona, which briefly pulled into a second-place tie with the Giants entering this weekend.
"I thought it was important for us to build some momentum," Bochy said. "I thought it was critical to get back on track, play some good ball and stay in the hunt. ... We're not where we want to be, obviously, but you want to hang in there."
The Giants accomplished that against the Phillies, capitalizing on facing the Major Leagues' worst team. They outscored Philadelphia, 27-9, while batting .393 (48-for-122) -- including .419 (18-for-43) with runners in scoring position.
Angel Pagan continued his weekend surge by going 3-for-4, though none of his hits figured in San Francisco's scoring. Pagan went 7-for-15 with four runs and four RBIs in the series, hiking his batting average from .261 to .271.