With the Giants behind, 1-0, entering the sixth and mustering just one hit against Orioles lefty starter Wei-Yin Chen, Scutaro tied it with a single and Pence put them ahead with a double for his first multi-RBI day since July 13.
San Francisco's win set up a rubber match Sunday against Baltimore (64-52). The Giants (52-64) have one home series win in their last seven.
"I'll say this: It's human nature to press a little bit," manager Bruce Bochy said. "But those guys have been around. They're pros. They came through today for us. Marco's been battling some aches and pains out there. You keep going, you keep grinding. It was a tough one last night."
On Friday, the Giants could not untie the game in the ninth inning with two on and nobody out before it went to extras and the eventual loss. On Saturday, it was the Orioles who struggled, going 0-for-8 with runners in scoring position.
"Pitching -- what a great job they did," Bochy said. "It started with Chad [Gaudin]. He logged some pitches there, but he competed so well out there to keep them to one run. Guillermo [Moscoso] had two solid innings. We needed it. He came through for us."
Added Baltimore manager Buck Showalter: "[We] just didn't cash the ticket when we had some opportunities. We got the game in some situations where we liked our chances; we just weren't able to get it done today compared to last night."
Gaudin was pretty much his usual self. He allowed one unearned run in the third following Brandon Belt's throwing error. Gaudin got out of a one-out, bases-loaded jam in the second, giving up two hits and three walks while striking out six through his five innings. With two outs, he got into a 3-0 count to Chen but got him to ground out. The inning was due to a "little mechanical flaw," Gaudin said, but he fixed it and was "grinding through five innings."
A former reliever, Gaudin hasn't allowed more than two runs in nine of his 11 starts.
"In the long run, you just have to base your emphasis on getting outs as quickly as possible and keeping it simple," he said.
Gaudin left with his pitch count at 93, and Moscoso worked two scoreless innings for his first victory of the season.
"We've got a lot of games left," Pence said. "We still have to continue to push and score more runs. The way our pitching has been, they're giving us every opportunity to get hot here."
The Giants' rally started with Andres Torres' leadoff single and pinch-hitter Gregor Blanco's sacrifice bunt. Scutaro scored Torres with a single to left. Belt followed with a double that hopped the fence in right-center field. Chen intentionally walked Buster Posey, and Pence followed with a two-run double near the right-field corner for a 3-1 lead.
Pence's double knocked out Chen (6-5), who entered with a 2.95 ERA but has been prone to yielding runs in the later innings this season.
"They were really aggressive the first five innings, and they watched me pitch for five innings already and were really patient in the sixth inning," Chen said through a translator. "They just kept waiting and waiting for my fastball and trying to hit my fastball.
"It was a little hard for me to adjust to the umpire's strike zone. The first five innings I felt like I could keep the ball down, but the sixth inning I felt like everything was up."
Closer Sergio Romo pitched the ninth for his 28th save. He allowed a leadoff single by Henry Urrutia and with two outs got home run leader Chris Davis to ground out to second. Davis slugged a moonshot of a solo home run to right-center, his 42nd homer, against Santiago Casilla to lead off the eighth and make it 3-2.
Romo said he didn't have any intention of walking the left-handed-hitting Davis to get to Adam Jones, who bats right-handed.
"I trust my stuff," Romo said. "Everybody here believes in my ability to get hitters out. ... I didn't try to dance around him. Sometimes you got to get the biggest out to win the ballgame."
In the third with Nate McLouth on first, Davis grounded one to Belt, whose throw to second hit McLouth on the back and bounced off shortstop Joaquin Arias' left foot toward center field. McLouth advanced to third on the throwing error and Davis reached first on the fielder's choice. McLouth scored an unearned run on a sacrifice fly with two outs to make it 1-0.
Batting in the No. 3 spot again, Belt went 2-for-4 and is hitting .464 in August.
"I've just got that feeling back that I've been searching for most of the season," Belt said.
With Belt heating up and the pitching continuing to roll, Pence believes that the team, though still in last place in the division, is turning a corner.
"If you lose and you're pitching well, you're not far off," he said. "That's the way I look at it."