DETROIT -- After waiting out a rain delay that lasted about as long as a normal game, Jake Peavy was convinced he could go back to the mound.
Giants manager Bruce Bochy wasn't about to stop him.
"He was so adamant that he was good to go," Bochy said. "I think it would have crushed him not to go back out there. You just trust Jake."
Peavy ended up pitching six innings -- three before the delay and three after it -- without allowing an earned run, and San Francisco routed the Detroit Tigers 8-2 on Friday night.
The Tigers fell two games behind first-place Kansas City in the AL Central -- and now trail Seattle by a half-game for the second wild card.
The Giants scored six runs in three innings against Rick Porcello (15-10) and led 6-0 when a severe storm came through downtown Detroit, delaying the game for 2 hours, 42 minutes.
When play resumed, Peavy (4-4) stayed in. He allowed two unearned runs in the fifth, but that was it.
"You just listen to your body. I felt good," Peavy said. "Tonight was a big one. Every game's big. We know that."
Playing in Detroit for the first time since winning the World Series there in 2012, the Giants scored a run in the first, three in the second and two in the third. Porcello allowed five earned runs and 10 hits in three innings, and dealt with an injury scare when a comebacker by Brandon Crawford hit his right foot in the third.
"The ball hit me between the ankle and the heel, and it's sore, but I'll be fine," Porcello said. "It isn't going to be a problem."
Porcello stayed in the game and got the third out of the inning. After the Tigers batted in the bottom half, the heavy rain moved in.
Sandoval's solo homer in the sixth -- his 16th of the year -- made it 8-2.
San Francisco opened the scoring on Sandoval's RBI single in the first, and Travis Ishikawa added one of his own in the second. Angel Pagan's run-scoring groundout made it 3-0, and Joe Panik's infield single brought home another run.
Panik actually made the third out on that play in strange fashion. Second baseman Ian Kinsler's throw got past first base, but catcher Bryan Holaday was backing it up. He threw to first, and Panik -- who appeared to have turned ever so slightly toward second after overrunning first -- was tagged out.
Peavy allowed six hits and struck out three.
After San Francisco's early barrage of hits, it became clear that the biggest threat to the Giants on this night likely would come from the weather. The game wasn't official yet when the delay started.
"If you looked at the radar, it wasn't pretty. We finally got a window there to get things going," Bochy said. "It was a long wait but well worth it. The last thing we wanted to do was start this thing over."
With debris sailing around in the wind, the Detroit grounds crew overcame difficult circumstances to put the tarp on the field. Head groundskeeper Heather Nabozny injured her right knee and had to have an MRI. The team said she is out indefinitely.
Saturday's game will start less than 13 hours after Friday's ended, and Detroit manager Brad Ausmus said he sent some of his players home after they were subbed out of Friday's loss.
"I told the guys that I took out of the game to go home and try to get some sleep with another game coming so soon," he said.
Giants: OF Michael Morse (strained oblique) received a cortisone injection, and the Giants hope he can return for the team's next series, at home against Arizona.
Tigers: RHP Joakim Soria threw off a mound and hopes to throw batting practice Monday as he works his way back from a strained left oblique.