DETROIT -- Michael Fulmer didn't right the ship -- he is the ship.

All-Star right-hander Fulmer, backed by productive at-bats from Justin Upton and Victor Martinez, fought through some sometimes faulty command Tuesday to pitch eight innings and lead the Detroit Tigers to a 5-3 victory over the San Francisco Giants that could for at least one day quiet talk the club would be dismantled later in the month.

Upton, taking his first swings since pregame Saturday, had two doubles plus a game-winning two-run single with two out in the seventh.

Martinez, 2-for-20 since coming back from an irregular heartbeat episode, had a solo home run plus an RBI single.

Fulmer (8-6) couldn't hang on to a 3-1 lead, giving up a two-run homer to Brandon Crawford in the top of the seventh, but registered a 1-2-3 eighth after the Tigers gave him another two-run margin.

Justin Wilson worked a scoreless ninth for his ninth save.

"I had a lot of 2-0, 1-0 counts early," said Fulmer, who gave up five hits, walked one and struck out five. "I did some cals (calisthenics) in the dugout; that got me loosened up. I gave up a lot of hard-hit balls early, the defense did a great job out there.

"Crawford hit a hanging 2-0 changeup. It's just another start, I was just trying to get another win, trying to put up another quality start. But I will think about the two home runs on the way home."

Fulmer (8-6) served up two home runs after not giving up one since April 29. He went 74 1/3 innings between his last home run allowed April 29 and Tuesday.

"He looked like he was struggling a bit with the location (early)," Giants manager Bruce Bochy said. "We extended some at-bats the first couple of innings but then he found it. He's got great stuff and he throws hard."

Nicholas Castellanos started the eighth with a single to center and Mikie Mahtook chopped a single to deep short. Jose Iglesias bunted but Castellanos was thrown out at third by Giants starter Matt Cain (3-8).

Reliever George Kontos got Ian Kinsler to fly to right but Alex Avila hit a slow single into the shift in short right and Upton slashed a 2-0 single to left to break a 3-3 tie.

"They got a break on the shift there," Bochy said. "I thought overall there Matty threw the ball fairly well. He's giving us a chance to win. We came back and tied it."

"I was very surprised," Upton said. "I expected some rust. I was surprised at being on time (with my swing), and with the pitches I saw. And with the way I felt."

Brandon Belt lined a double to right-center with one out in the seventh, the first hit Fulmer allowed since the third, and Crawford lofted his seventh home run just past the railing atop the wall in right center, tying the score at 3.

"He (Cain) is out there in the seventh, tie ballgame, got in a little jam, got a bad break on that high chopper that just got through," Bochy said, "but he got the big out on the bunt and the order was turning over, it would have been the fourth time he faced them, so I made the change there."

Upton walked to open the fourth and Miguel Cabrera singled. Martinez drove Upton in with a single to right, breaking the 1-1 tie, and Castellanos scored Cabrera with a first-pitch sacrifice fly to center.

The teams swapped early solo home runs to create a 1-1 tie.

Hunter Pence swatted his sixth with two out in the first off Fulmer for San Francisco while Victor Martinez countered for Detroit with his sixth, which also went over the right-field fence.

"We did a lot of good things," Bochy said."Crawford's home run, that's huge. We're facing a pretty good pitcher there, he made the All-Star team. So if you go into the seventh tied, you take it. They got a couple break there in the seventh inning and that was the difference in the game."

Detroit entered the day with a 36-45 record that was its worst after 81 games since losing 119 contests in 2003 and speculation has increased that the Tigers would be dealing some of their bigger contracts as the July 31 non-waiver trade deadline approached.

NOTES: It was RHP Michael Fulmer's suggestion he move up a spot in the rotation so he could pitch Tuesday and Sunday. "We thought about it for maybe 10 seconds," Detroit manager Brad Ausmus said, "and said, 'Yeah, that's probably a pretty good idea.'" ... San Francisco 3B Eduardo Nunez was recalled from his rehab assignment when he didn't feel right after five innings for Double-A Richmond. He'll get treatment with the Giants. ... Giants manager Bruce Bochy said C Buster Posey would DH the first two games of his team's interleague set in Detroit. ... LF Justin Upton returned to the Tigers' lineup Tuesday after missing three games with a sore right side but 1B Miguel Cabrera left after six with left hip tightness.