SAN DIEGO -- The Padres haven't spoiled anything when it comes to the Los Angeles Dodgers.

But they are making life miserable for the National League West's other playoff contender -- the San Francisco Giants.

Right-hander Edwin Jackson (5-6) held the Giants to two runs over six innings Friday night and Wil Myers put the Padres ahead to stay with a three-run homer in the first as the Padres defeated San Francisco 7-2 at Petco Park.

The loss, coupled with the Dodgers' 5-2 victory over Colorado, left the Giants seven behind with eight to play.

San Francisco, which is 4-8 over its last 12 games, fell one game behind the New York Mets in the National League wild-card race but holds a half-game lead over St. Louis for the second wild-card berth.

The win was the Padres seventh in eight games against the Giants since the All-Star break after the Giants won the season's first nine meetings.

"These bats have just been quiet," said Giants manager Bruce Bochy. "It's critical to rip off a bunch of wins. What's going to happen is pretty simple. We've got to pitch and we've got to get these bats going. We can't put this kind of pressure every night on the pitchers. We've had a tough time scoring runs against the Padres.

"It's hard to get a consistent run without the offense going. And tonight, with four hits and two runs ... we're down three right away so obviously that's not going to make it."

The Giants scored nine runs in their last five games against the Padres. On Friday, they were down 3-0 before the bottom of the first was nine pitches old. The Padres expanded the lead to 7-2 in the fifth as left-handed Giants reliever Matt Reynolds gave up four runs without retiring a hitter.

Both Padres rallies started the same with a lead-off single by Jon Jay followed by a double by recent callup Carlos Asuaje to put runners at second and third.

After Jay opened with a single and Asuaje doubled him to third for his first major league hit, San Francisco right-handed starter -- and loser -- Albert Suarez (3-5) gave up the three-run shot to Myers.

Myers continued his torrid hitting at Petco Park with a three-run homer -- a 406-foot drive to center. The homer was Myers 28th of the season and 18th at Petco Park. Myers holds single-season records at Petco for hits (91), homers and RBIs (56).

Myers' homer was also the Padres' 76th this season in their downtown home, another single-season record for the 13-year-old venue.

After failing to score despite excellent opportunities in the second (runners at second and third two out), third (lead-off double) and fourth (two on, none out), the Giants broke through for two runs in the fifth off Jackson, who is 5-5 with the Padres.

Jackson issued back-to-back walks to Denard Span and Angel Pagan ahead of a full-count, two-run double off the wall in left center by Buster Posey. Up to that point, the Giants had been 0-for-7 with runners in scoring position.

"All in all, this was a decent bounce-back game," said Jackson, who gave up eight runs in 4 1/3 innings in his previous start in Colorado. "I slipped a bit in the fifth, but that inning could easily have been worse."

"Edwin lost his command a bit in the fifth," Padres manager Andy Green said.

With four of the next five Padres being left-handed as the fifth inning opened, Bochy opted for left-handed reliever Matt Reynolds. The move backfired.

Jay and Asuaje repeated their first-inning hits. Reynolds walked Myers to load the bases, then threw a four-pitch, bases-loaded walk to Ryan Schimpf. Alex Dickerson followed with a two-run single down the line in right before catcher Austin Hedges drove home Schimpf with a sacrifice fly to left.

"Left-handed pitching is something we haven't done well against," Green said. "It was good to see Asuaje hit the ball like that ... up and down, we did a good job against the left-hander."

Jackson allowed four hits, five walks and struck out five.

Suarez lasted four innings and gave up three runs and five hits.

NOTES: The Giants still have not named a starting pitcher for Sunday. It is Johnny Cueto's turn, but he suffered a strained left groin in his last start and is doubtful. LHP Ty Blach could get the start. ... Giants SS Brandon Crawford (dislocated finger) could return Sunday. ... LHP Madison Bumgarner, the Giants' Saturday starter, could be in line to start the National League wild-card game if the Giants are in it. ... After allowing only two runs on three hits Thursday night, Padres LHP Christian Friedrich will make his scheduled final start.