HOUSTON — It was tough to spot the contender over the weekend at Minute Maid Park, which doesn’t speak well for the Giants. Their opponent was on pace for a 108-loss season.

But there is no mistaking Pablo Sandoval’s All-Star swing.

A beaten-down Kung Fu Panda delivered when nobody else could, lifting a two-run home run to the opposite field in the 11th inning that sent the Giants to a 6-4 victory over the Houston Astros on Sunday afternoon.

Although his right shoulder remained too sore to swing right-handed, the switch-hitting Sandoval mustered up the difference-maker off right-hander Mark Melancon, and local boy Brandon Belt popped a three-run homer as part of a career-best, four-hit afternoon.

The Giants used six pitchers and every last muscle fiber to avoid being swept in three games by the team with baseball’s worst record. Most vitally, the victory allowed the Giants to inch within 1½ games of the N.L. West-leading Arizona Diamondbacks, who lost their fifth consecutive game.

For all their whirlwind of injuries on a dripping, disappointing, challenging and grueling 4-6 trip, it wasn’t a widow-maker. The Giants return home trailing Arizona by just a half-game more than when they left the cooler climes of AT&T Park.

Torture? Sure. But there’s a different one-word motto this season: survival.

“The best way I can put it is, we survived,” said Giants manager Bruce Bochy, who looked as if he needed his vitals

checked. “It wasn’t great by any means. To win the last one, we survived it. We’re not too far back, for which we’re fortunate. We know it.

“That’s one of the hardest-fought wins I think I’ve ever been involved in.”

It started off promising enough. Belt hit his three-run shot in the second inning to delight his friends and family, many of whom wore T-shirts with a baby giraffe — his clubhouse nickname — and a “Keep Belt Awkward” slogan.

“I was hating life yesterday,” said Belt, who was 0 for 4 and once lost track of the outs Saturday. “I was so eager to see all my friends and family, and I didn’t do so good. I came in today and just wanted to clear my head and put the bat on the ball. If I can keep it that simple, that’s when I’ll be at my best.”

Belt’s home run off former minor league teammate Henry Sosa was the Giants’ first three-run shot since Brandon Crawford hit one July 2. Before that, they hadn’t hit a three-run homer since Freddy Sanchez on June 2.

In addition to filling their monthly quota, the homer provided a margin that had been safe all season. The Giants entered the game 32-0 whenever they held a three-run lead.

It wasn’t that easy, though.

For all the offensive ineptitude that Bochy has witnessed this season, nothing turns his size 81/8 cap into a pressure cooker more than when his pitchers issue walks. Spot starter Dan Runzler issued three of them, including one to Sosa, and checked out in the middle of Houston’s four-run second inning.

“Now you’re beating yourself,” Bochy said. “We knew it’d probably be a bullpen day, but I didn’t think we’d start in the second inning.”

Belt’s single contributed to the Giants’ tying rally in the fourth, when Mike Fontenot’s sacrifice fly scored Nate Schierholtz.

But the Giants couldn’t push ahead. An invisible force field seemingly kept them from breaking a tie as they stranded seven runners over the seventh, eighth and ninth innings — with each missed chance more calamitous than the previous one.

Sandoval, batting lefty-on-lefty, struck out to strand two runners in the seventh. The Giants also saw Schierholtz thrown out trying to score on a moderately deep fly ball in the eighth; Schierholtz flied out with the bases loaded in the ninth.

But the Giants bullpen held firm. Jeremy Affeldt survived a bases-loaded, one-out jam in the ninth to force extras and give Sandoval another chance.

A day earlier, Sandoval said he felt “like (crap).”

And now?

“I still do. I’m tired,” he said, nursing a badly bruised foot, too. “I just look for one pitch. I got it. This is for us. It’s important for us.”

Bochy said nobody needs Monday’s day off more than his All-Star third baseman.

“Well, early on he looked like he felt,” Bochy said. “You know I love Pablo. Those last two at-bats were good ones. That’s what you hope your 3-4 hitter does for you late in a ballgame.”

Late in a season, too — one in which the banged-up Giants, amazingly, are still relevant.

“We’re strong,” Sandoval said. “We’ve got a new team. Guys are playing hurt. The team we’ve got, if we keep playing like we did early, we’ll do a lot of things. We can get there again.”

For more on the Giants, see Andrew Baggarly’s Extra Baggs blog at blogs.mercurynews.com/extrabaggs.

Sanchez is scheduled for another rehab start

Philadelphia Phillies aces Roy Halladay and Cliff Lee aren’t the only notable pitchers scheduled to miss the highly anticipated NLCS rematch series that begins Tuesday, when the Giants arrive at Citizens Bank Park.

Jonathan Sanchez won’t pitch in Philadelphia, either. Giants manager Bruce Bochy confirmed that he wants Sanchez to make one more rehab start for Triple-A Fresno and stretch his pitch count beyond 100 before the coaching staff would look at ways to work him back into the rotation.

It’s a frustrating decision for Sanchez, who said his arm felt good while striking out eight in five innings for Fresno against Colorado Springs on Friday. Even though Sanchez won the N.L. West clincher for the Giants in last year’s regular-season finale, for the moment, he feels like the odd man out.

“I don’t think I’ll pitch till September,” said Sanchez, shaking his head. “What are you going to do? I’m ready, but everyone is pitching good. I can’t say anything, you know?”

Sanchez said his biceps tendinitis, which affected his arm speed, wasn’t an issue as he threw 85 pitches against Colorado Springs. He made a mechanical tweak, moving his glove closer to his body in his delivery, in an effort to keep his arm from dropping. He said he’s throwing more strikes as a result.

Tim Lincecum, Barry Zito and Matt Cain are scheduled to pitch in Philadelphia. The

Phillies are listing young right-hander Vance Worley, Cole Hamels and Kyle Kendrick as their probables.

Symbolically, Tim Lincecum walked to the mound against Cincinnati on Saturday as the Giants’ last line of defense against the forces of panic and despair.

It’s not quite fair to pile all that responsibility upon anybody’s shoulders in any single game in June, but there it was.

Freddy Sanchez had just gone down to a serious shoulder injury. Buster Posey has been down and out for a few weeks, of course.

The season is still young, and the Giants are still clinging to first place in the National League West.

But if the Giants were going to have a chance to feel halfway good about themselves this weekend, Lincecum was the one who had to start the party music.

And it did not happen.

Instead, after the Reds’ 10-2 victory at AT&T Park, there was mostly thick silence in the Giants’ clubhouse.

“It’s not about carrying the team, it’s just being a large aspect of it, and doing your job,” Lincecum said after giving up seven earned runs in four-plus innings, one of the worst outings of his glorious career.

“And I didn’t do mine today.”

What happens to the defending World Series champions if they can’t hit, if they don’t have Posey, and if Lincecum isn’t on top of his game?

We saw it Saturday — the sense of anxiety was a tangible presence amid the murmuring and the head-scratching in the stands.

Lincecum has done so much for this franchise, when he doesn’t deliver, the air gets mighty arid.

“I

know it looked bad today,” manager Bruce Bochy said. “We were off. Had a horrible game. This doesn’t happen very often. It just so happens it comes right after Freddy’s injury. These guys don’t make excuses.

“These guys, they’re not making excuses. “… It’s up to us to keep fighting. And these guys will.”

Usually, the charge starts with Lincecum, of course.

But this was the fourth consecutive — and easily the worst — sluggish outing for the two-time Cy Young winner, all dating to May 21, when Lincecum shut out the A’s.

In that game, Lincecum threw a season-high 133 pitches; that also was his last start before the Giants lost Posey, Lincecum’s trusted catcher, to a devastating ankle injury in late May.

In his four starts since, Lincecum has a 7.66 ERA, and his season ERA has gone from 2.06 to his current 3.41.

Lincecum had a similarly wobbly period last August, when he acknowledged some adjustment issues going from Bengie Molina to Posey behind the plate.

By last September, though, Lincecum was in lock step with Posey and was nearly perfect through the fall.

Right now, Lincecum is about as far from his September-October dominance as he can get.

“I still feel strong,” Lincecum said. “I don’t feel unhealthy. I don’t feel like anything’s bothering me. It’s just simply getting back to being me. Just driving to the plate, using the mechanics, keeping my rhythm.

“Kind of dumbifying myself, I guess you could say “… keeping it simple.”

Lincecum was all over the place from the outset, and the Reds were disciplined enough to make him pay; he threw 73 total pitches, only 36 for strikes.

He recorded only one strikeout, which, remarkably, is the lowest total of his career. In 136 previous outings (135 as a starter) — Lincecum had never recorded fewer than two strikeouts and had averaged 7.4 strikeouts per appearance.

That 133-pitch outing, in retrospect, sticks out like a sore statistical thumb.

“I don’t feel like it’s fatigue,” Lincecum said when asked about the effects of the May 21 game. “I don’t feel like I’m getting tired. I don’t feel like anything’s broken. I just feel like it’s a matter of just getting back to being me.”

That, perhaps, could suggest Lincecum has been thinking a little more on the mound now that he’s throwing to Eli Whiteside, not Posey.

In the third inning, there might have been a sign of some disconnect — with a runner on third, Lincecum threw a darting off-speed pitch that hit the dirt but looked stoppable.

Whiteside missed the ball, it skipped to the backstop, Brandon Phillips scored, putting the Reds up 3-0 and putting a scowl on Lincecum’s face.

Has the catcher change affected Lincecum at all?

“Not really,” Lincecum said. “Not at all. I mean, when you go out there, whether it’s with Whitey or (Chris) Stewart, you have to go out there and make pitches.”

Bochy said he continues to have the utmost confidence in Whiteside but added that he might get Stewart in there with Lincecum if the schedule works out right.

You count up all of the Giants’ woes, and you do have to ask: How much has to go wrong for them to be knocked out of first place?

At some point, it probably will come down to Lincecum, the Giants’ other key pitchers, and the refortifying of their last line of defense.

Read Tim Kawakami’s Talking Points blog at blogs.mercurynews.com/kawakami. Contact him at tkawakami@mercurynews.com or 408-920-5442.