A botched grounder led to a three-run deficit, and they were in danger of falling behind the Kansas City Royals three games to one.
Instead of panic, it was time for some Panda-monium.
Pablo Sandoval's single set up Hunter Pence to score the tying run in the fifth inning and the 2012 Series MVP followed with a go-ahead, two-run single in the sixth that sent the Giants surging past the Kansas City Royals 11-4 Saturday night at pulsating AT&T Park.
The Series is tied at two games apiece, ensuring the title will be decided at Kansas City's Kauffman Stadium next week.
"We never give up, that's the thing," said Sandoval, who shook off a stomach bug after starting to feel ill Friday. "We've been doing it all year in these situations. We know how that feels."
Pence, eyes ablaze, had three hits, three RBIs and a nifty sliding catch in the ninth inning, and Joe Panik hit a two-run double in a four-run seventh.
"We had to win this game tonight no matter what," said Giants starter Ryan Vogelsong, knocked out after 2 2-3 innings.
San Francisco scored 10 unanswered runs and piled on 16 hits in a marathon of exactly 4 hours.
"We're going to battle and scratch and claw," Panik said.
Madison Bumgarner tries to put the Giants ahead Sunday night when he starts against Royals ace James Shields in a rematch of the opener, won by the Giants 7-1.
"This was a great ballgame, I thought, especially the way we came back," Giants manager Bruce Bochy said.
Showcasing baseball at its exciting best, the game included a sprawling catch by Royals centre fielder Jarrod Dyson that left a pair of divots, and the first use of expanded video review in Series history — which became a turning point. Jeff Kellogg's safe call at second base was upheld by replay ump Jerry Meals on catcher Salvador Perez's pickoff attempt of Joaquin Arias, helping the Giants build the pivotal rally.
Four fans in the first row near the Giants dugout wore giant — of course — white panda heads as they cheered on Sandoval, nicknamed Kung Fu Panda and a veteran of the team's World Series titles in 2010 and '12. The switch-hitter batted just .199 right-handed during the regular season but came up with his first two-hit game from that side of the plate since Aug. 25, emphatically tossing his bat after lining a single to centre that put the Giants ahead 6-4.
Sandoval said he vomited after batting practice and took medication.
"No one was taking me out of the lineup," he said. "I play giving my heart and soul to the team."
Lost in the torrent of runs was the earlier fit of pique by Bochy, who threw his hat to the dugout floor when his team botched a third-inning grounder. The mood was different by the eighth, when former Journey singer Steve Perry sprinted to the front row of the second deck behind home plate and led the crowd of 43,066 in a sing-along of "Lights."
The outlook seemed far different in the third , when ominous, dark clouds formed over the bayside ballpark, and the Royals burst ahead 4-1 against Vogelsong with the pitcher's help. He failed to step on first while covering and trying to catch Brandon Belt's throw on Eric Hosmer's tapper. Orange-clad fans quieted, and there even were scattered boos.
"I thought we had the situation right in the palm of our hand," Royals manager Ned Yost said.
But Yusmiero Petit settled the NL champions with three innings of scoreless, two-hit relief to improve to 3-0 in the post-season.
"The way Petey threw tonight saved our bullpen. He was our MVP tonight for me," San Francisco pitcher Jeremy Affleldt.
Yost stayed with starter Jason Vargas into the fifth, removing him after Panik's leadoff double. Royals relievers had been 7-0 in the post-season, but Yost couldn't get to his hard-throwing HDH triad of Kelvin Herrera, Wade Davis and Greg Holland.
Jason Frasor and Danny Duffy combined to allow the tying run in a two-run fifth. And Brandon Finnegan, the first player to appear in the College World Series and World Series in the same year, allowed Sandoval's two-run single and Brandon Belt's RBI's single in the sixth.
"I don't think anybody goes through a season without losing a game," Finnegan said. "If they did they'd be in the Hall of Fame now."
Kansas City went ahead with a two-out, four-run rally in the third with the help of two infield hits that gave the Royals 18 in the post-season, matching the total of all other teams combined. Omar Infante grounded a two-run single up the middle for a 3-1 lead, and Perez followed with a bloop RBI single.
"Occasionally I do show emotion in that dugout," Bochy said of his cap toss.
Buster Posey cut the deficit in the bottom half with a run-scoring single, tying Barry Bonds' team record of 21 career post-season RBIs. Pence's RBI single in the fifth caused Frasor to throw up both arms in frustration, Sandoval singled Pence to third and Juan Perez's sacrifice fly made it 4-all.
"Oh, man, somewhere inside of me secretly I had hoped that it would go seven games for the excitement and the thrill of it," Yost said. "Sure looks that way."
Royals: Shields has a 7.11 ERA this post-season, totalling 19 innings in four starts.
Giants: Bumgarner is 3-1 with a 1.40 ERA in five post-season starts this year.
PITCHERS AT THE PLATE
Vargas became the first AL pitcher to bat twice in a Series inning since Boston's Luis Tiant in the 1975 opener.
Eleven Giants had hits, including three of 10 in the No. 9 spot; Petit's single made him the first Giants reliever to get a Series hit since Slick Castleman in 1936.