Angel Pagan hit a tiebreaking single in the eighth inning to cap San Francisco's rally from a four-run deficit and the Giants went on to beat the Colorado Rockies for the eighth straight time, 9-6 on Tuesday night.
Brandon Crawford hit a three-run homer to start the comeback and Hunter Pence had a pair of RBI singles for the Giants, who have won the first two games of the series.
Dexter Fowler and Josh Rutledge each drove in two runs in a five-run second inning against Tim Lincecum, and Troy Tulowitzki added a solo homer off the former Giants ace to help the Rockies build a 6-2 lead.
But the Giants scored four runs in the sixth to tie the game and then won it in the eighth against Matt Belisle (0-1).
Pinch-hitter Andres Torres started the winning rally with a double to right field and Pagan followed with a single up the middle that almost hit Belisle in the face.
Pablo Sandoval and Gregor Blanco added RBI singles to give the Giants insurance.
Santiago Casilla (1-0) pitched a perfect eighth for the win and Sergio Romo got three outs for his fifth save.
The Rockies appeared to be in control until Juan Nicasio walked the first two batters of the sixth to end his night after 95 pitches, marking the 110th straight game a Rockies starter has failed to reach the 100-pitch mark.
Adam Ottavino came in and allowed Crawford's second career homer at AT&T Park. The Giants then loaded the bases with one out before Belisle relieved and allowed a tying single by Pence that gave him 1,000 career hits. Belisle escaped the jam without further damage when he got Brandon Belt to hit into an inning-ending double play.
Lincecum, a two-time NL Cy Young Award winner, is still trying to find his groove following a disappointing 2012 season when he had a career-high 15 losses and an NL-worst 5.18 ERA.
After matching a career high with seven walks in his first start last week against the Los Angeles Dodgers, Lincecum was hurt again by a lack of command against the Rockies.
He needed just nine pitches to work through a perfect first inning before being able to find the plate in a five-run second.
He walked three batters, including the pitcher for the second straight start, and also threw a wild pitch.
But he might have come out of that inning unscathed if not for a bad decision by second baseman Marco Scutaro, who threw wildly trying to get a force at second base instead of taking a sure out at first. That helped set up the big inning that featured a two-run double by Fowler and a two-run single by Rutledge.
Lincecum retired nine of 10 batters following Rutledge's single, allowing only another walk to Nicasio. But Tulowitzki added to the Rockies' lead when he sent a first pitch halfway up the seats in left field for his third homer of the season.
Colorado has homered in all eight games.
Lincecum allowed six runs, four hits and four walks with seven strikeouts in six innings.
NOTES: Nicasio became the first pitcher to draw two walks in one game against Lincecum. ... With a day game Wednesday, Giants manager Bruce Bochy gave reigning NL MVP Buster Posey the night off and started Hector Sanchez at catcher. Bochy said Sanchez could end up being Lincecum's regular catcher but he doesn't want to commit to that yet. ... Barry Zito, who is 7-2 in his career vs. Colorado, will start the series finale against Jeff Francis.