The win, coupled with Arizona's 8-2 loss to St. Louis on Tuesday, moved the Rockies to within five games of the Diamondbacks in the NL West.
"We're right about where we were last year, ready for another crazy run," Spilborghs said.
While the Rockies are still eight games under .500, their position in the division is almost exactly the same as it was last year. Through games of Sept. 2, 2007, the Rockies were five games behind Arizona and San Diego, in fourth place. This year, they're in third.
Colorado won 14 of their final 15 regular season games last year to win the NL wild card, and advanced to the World Series by winning seven straight.
"We're going to play until they shut the lights off and we come up short," Rockies manager Clint Hurdle said.
Quintanilla started the winning rally with a single off of Keiichi Yabu (3-6), and Matt Holliday walked. Giants closer Brian Wilson came on and Spilborghs lined a single down the right-field line to end the game.
"I'm confident in those situations," said Spilborghs, who has three game-winning hits this season. "If you get a hit, you're a hero. If you don't, you keep grinding. I feel like I can't fail."
Troy Tulowitzki homered for the Rockies, his sixth of the year.
"Tough loss," Wilson said. "You don't like to lose. Ever. We haven't given up. That's what makes it so tough to lose."
Jason Grilli (3-1), the sixth Colorado reliever, struck out four and walked one in three innings of relief for the Rockies, who have won seven of 10.
"I'm not typically going three innings," Grilli said. "I felt good enough, and I kept telling myself, 'Don't give in and I'm not losing this game. I'm not to be the guy in the loss column in this one."
"We hit a few hard balls after we tied the game, but couldn't find a hole," Giants manager Bruce Bochy said. "They did and that was the difference."
Tim Lincecum dominated Colorado for the first three innings, striking out four and not allowing a hit, but he faltered in the fourth when he gave up five runs and threw two wild pitches.
Quintanilla, who led off the fourth with a single, scored on Holliday's single. Brad Hawpe doubled down the right-field line to drive in Holliday, and Chris Iannetta's single up the middle made it 3-0.
"I made a bad pitch to Tulowitzki," Lincecum said. "It was set up for a changeup on the outside and I left it fat in the middle of the plate."
Lincecum struck out six and walked two in five innings.
The Giants got two back in the fifth on Vizquel's double to right made it 5-2. They tied it in the sixth and chased Colorado starter Livan Hernandez.
Luis Vizcaino replaced Rusch, struck out pinch-hitter Fred Lewis and had an 0-2 count on Emmanuel Burriss before Burriss singled home two runs. Vizquel singled to tie it before Vizcaino struck out pinch-hitter John Bowker to end the inning.
Hernandez gave up five hits and four runs in 5 1/3 innings. He didn't strike out a batter and walked two.
Former Baltimore Orioles great Cal Ripken Jr. was in attendance. ... Holliday's RBI in the fourth inning was his first since Aug. 23, a span of nine games.