The Giants started their bid for a second World Series title in three years by getting to Detroit ace Justin Verlander and eventually recording 11 hits against six Detroit pitchers.
Less than a week ago San Francisco was facing elimination from the playoffs after falling behind 3-1 against St. Louis in the National League Championship Series. Since then the Giants have won four in a row -- three against the Cardinals and the World Series opener against Detroit -- by the combined score of 28-4.
San Francisco will host Game 2 on Thursday before the best-of-seven series moves to Detroit on Saturday.
Sandoval hit a solo homer in the first, a two-run blast in the third to finish off a three-run inning and added a solo shot in the fifth. In his fourth and final at-bat of the game he rocketed a single up the middle.
Sandoval has hit six home runs in the 2012 playoffs, half as many as he produced during the entire regular season while playing in 108 games. The record for most home runs in an entire World series is five -- held by Jackson and Chase Utley.
The first two homers by Sandoval were hit off Verlander, who in his three previous playoff starts this year had gone unbeaten with an earned run average of 0.74. He had struck out 25 in his previous 24 1/3 innings.
Verlander made it through just four innings in Game 1, giving up five runs on six hits.
San Francisco starter Barry Zito, the winning pitcher in the first of San Francisco's three must-win triumphs over St. Louis, allowed a run on six hits over 5 1/3 to get the victory. He also singled in a run in the fourth to give San Francisco a 5-0 lead.
Detroit, playing for the first time in six days, was not only outhit and outpitched but also came up short in the good-fortune department.
The game took a decided turn in San Francisco's favor in the third inning when a two-out chopper down the third base line by Angel Pagan hit the bag and bounced past Miguel Cabrera into left field.
Pagan legged it out for a double, after which Marco Scutaro singled him home. Scutaro then came in on Sandoval's second homer of the game. Scutaro and Buster Posey also had RBI singles in the seventh.
The first Detroit run came in the sixth, when Cabrera singled in Austin Jackson. The Tigers put two on with two away later in the inning before Tim Lincecum came in to relieve Zito. Lincecum struck out Jhonny Peralta to end the threat. Peralta hit a two-run homer in the ninth to close the scoring.
Doug Fister will take the mound for the Tigers on Thursday. San Francisco will start Madison Bumgarner, who has lost his only two decisions in this year's playoffs.