SAN FRANCISCO -- In the grand scheme of things, the San Francisco Giants' 9-1 victory over the San Diego Padres on Friday night made a very small dent in the Los Angeles Dodgers' very large lead in the National League West.

But comebacks have to start somewhere, winning pitcher Jake Peavy insisted afterward.

"We're a game closer, aren't we?" Peavy said after recording his first-ever win over the team that drafted him 16 years ago.

The victory in the opener of a nine-game homestand, coupled with the Dodgers' loss at Arizona, allowed the Giants (73-68) to creep within 7 1/2 games of the NL West leaders with 21 games to play.

"We know the task ahead," Peavy said. "We need to win about all of them. We want to get within striking distance.

"There isn't anybody in this locker room going to give up."

The Giants have four games remaining with the Dodgers, a home series in the final week of the season.

Right fielder Marlon Byrd had three hits and second baseman Kelby Tomlinson scored three times for the Giants, who were coming off a 3-7 trip that sent them to the edge of elimination in their quest to repeat as World Series champions.

"We all are (scoreboard-watching)," Giants manager Bruce Bochy said. "It's been a while since we picked up a game (on the Dodgers). You never know.

"The one thing we can control is to go out there and win ballgames. You never lose hope. It's evident we need some help."

Peavy (6-6) gave up a second-inning home run to Padres left fielder Justin Upton, and then not another hit until Upton singled with two outs in the seventh, by which time the Giants had turned a 1-0 deficit into a 5-1 advantage.

Minor league call-up Jarrett Parker, pinch-hitting for Peavy, crushed a run-scoring, ground-rule double and third baseman Matt Duffy added a two-RBI single in a four-run seventh, after which the veteran turned over a 9-1 lead to the San Francisco bullpen.

In recording his third consecutive victory, Peavy allowed just the one run on two hits in his seven innings. He struck out two and did not walk a batter.

Peavy had been 0-1 with a 5.00 ERA in two career starts against his former club.

"I enjoy competing," he said. "I know a lot of people in that (Padres) dugout. Other than that, it was just another game -- a game we had to win."

Every Giants starter, including Peavy, had at least one hit as San Francisco teed off on Padres right-hander Andrew Cashner (5-15) and three relievers for 14 hits.

"The results aren't obviously what you want, but I don't feel like I pitched that bad," Cashner said. "I made a few mistakes. But I also had some groundballs that weren't right at guys."

Duffy and shortstop Ehire Adrianza had two hits apiece for the Giants, who have won 17 of their last 22 home games.

The loss dropped the Padres (67-75) 1 1/2 games behind Arizona (68-73) in their duel for third place in the NL West.

San Diego, which totaled four hits off four Giants pitchers, was opening a nine-game trip on the heels of a 4-7 homestand.

"He hit his spots," Padres interim manager Pat Murphy said of Peavy. "What can you say? He pitched his (butt) off tonight. He kept he pressure on. He was relentless."

After Upton's home run, his 25th of the season, opened the scoring in the second, the Giants rallied into a commanding position by scoring one run in the bottom of the second, two in the third and two in the fifth.

Consecutive inning-opening singles by left fielder Alejandro De Aza, Duffy and catcher Buster Posey triggered the two-run, tie-breaking third.

Posey's single scored De Aza to give the Giants the lead, and one out later Byrd singled home Duffy for a 3-1 advantage.

Two-out RBI singles by Adrianza and Peavy produced the fifth-inning runs, increasing the San Francisco lead to 5-1 and also spelling the end of the night for Cashner.

Cashner allowed nine hits and five walks in his 4 2/3 innings, surrendering five runs. He struck out seven.

NOTES: Giants RHP Jake Peavy has now recorded at least one win against every National League team. ... Padres RHP Andrew Cashner became the 29th pitcher in franchise history to start a game on his birthday, his 29th. ... Padres LF Justin Upton, who missed Thursday's game against Colorado after having two ingrown toenails removed, returned to the starting lineup. ... The Giants play 16 of their final 22 games at home, the highest number of remaining home games in the NL ... The Giants reinstated RHP Matt Cain (nerve irritation in right elbow) from the 15-day disabled list before the game, and recalled OF Jarrett Parker from Triple-A Sacramento. ... Giants OF Gregor Blanco was diagnosed with a concussion Friday and did not play in the series opener.