SAN DIEGO -- The Giants accomplished a lot to win by a little.
Buster Posey played the type of game that few others besides Buster Posey can summon. Tim Lincecum delivered a tough, unrelenting effort. San Francisco's bullpen excelled yet again after Lincecum departed.
Yet all of these admirable performances in the Giants' 4-3 victory Sunday might have been nullified had it not been for manager Bruce Bochy's successful challenge of an umpire's ruling in the third inning. The overturned decision denied San Diego a run, ended the inning and prevented Lincecum from taxing himself by throwing more pitches.
"Obviously, it changed the game today," Bochy said without a trace of boastfulness after the Giants ended their three-game losing streak and averted a Padres series sweep.
Though the Giants didn't know it when the pivotal play developed, they were on a collision course with more offensive futility. It didn't seem that way after Posey's two-run homer and Angel Pagan's two-run single gave San Francisco a 4-0 lead after two innings. But after Pagan's knock, San Diego starter Robbie Erlin and three relievers no-hit the Giants for the final 7 2/3 innings.
So the Giants needed truth, in the form of baseball's new replay system, on their side at Petco Park.
With two outs and the bases loaded, Chase Headley lashed a double into the right-field corner. Will Venable and Seth Smith scored easily. Xavier Nady, who walked to fill the bases, also tried to come home. Posey applied a sweeping tag upon Nady, who originally was ruled safe by plate umpire Mike DiMuro.
Bochy requested a video review, which caused the call to be overturned, since replays showed that Posey brushed Nady's back with his glove before any part of his body made contact with home plate.
"I felt he tagged me before I reached the plate," Nady acknowledged.
Momentum, which swung to the Padres as seemingly half their roster scampered around the bases, returned to the Giants. They barely survived the rest of the way as they participated in their ninth one-run decision in 10 games. Their total margin of victory in that span is 11 runs.
"Unbelievable, man," Bochy said. "I've been in a few runs where you played tight games, but never like this."
Posey continued to neutralize San Diego's offense by throwing out Everth Cabrera on a fifth-inning stolen-base attempt. After apprehending 26 percent of basestealers last year (31 of 118), Posey has improved to 39 percent (seven of 18).
Earlier, Posey's first-inning homer, a drive to left field that traveled an estimated 427 feet, set an upbeat tempo for the Giants.
"I think my timing's been off a little bit," said Posey, who entered the game in a 1-for-24 skid. "I think I was on time much better today."
Lincecum considered Posey's multidimensional contributions and said, "Overall, he covered all facets of the game."
Lincecum also was thorough as he recorded his 90th career victory. Though his afternoon ended when he yielded Nick Hundley's home run to open the seventh inning, the right-hander displayed his typical resourcefulness while striking out at least one batter in every complete inning he pitched except the third.
"I felt he did a great job of keeping the ball down all day and elevating it at the right times," Posey said.
San Francisco's bullpen, which leads the Majors with a 1.79 ERA, preserved the one-run edge Lincecum bequeathed with some slick work. Left-hander Jeremy Affeldt, making only his second appearance since leaving the disabled list, defied the percentages by retiring right-handed pinch-hitters Chris Denorfia and Jedd Gyorko while taking care of the seventh inning.
"That's the nice thing about Jeremy -- he's got the good sinking fastball, split and curveball, so he's effective against righties, too," Bochy said.
Santiago Casilla coaxed Nady's double-play grounder to end the eighth before Sergio Romo retired three consecutive batters with Headley on second base to convert his fifth save in as many chances.