SAN DIEGO -- Buster Posey homered and had two RBIs as the San Francisco Giants survived Johnny Cueto's abbreviated outing to beat the San Diego Padres 5-4 on Friday night.

The win might have been costly as Cueto exited the game with two fingers and a thumb on his pitching hand showing signs of blisters. Cueto might miss his next start, according to Giants manager Bruce Bochy.

"You could tell he wasn't quite right," Bochy said. "That was what kept him from going out there. After the fourth inning he said, 'I can't finish my pitches' so I had to make a move.'"

Posey, who entered the game with two hits in his last 19 at-bats, produced a seventh-inning, 429-foot blast off reliever Ryan Buchter for his 11th homer on the year and his first since June 22.

Posey had his first RBI when he singled in the game's initial run.

Gorkys Hernandez had a career-high four hits to lead the Giants' 14-hit attack.

Cory Gearrin (3-2), who relieved Cueto, secured the win after pitching a scoreless inning.

Sam Dyson worked the ninth for his fourth save, but not before the Padres scored once and had the tying run at third when Jabari Blash flied out.

"It got kind of exciting there at the end," Bochy said.

Cueto escaped without a decision and has won just twice in eight starts; last year he was 13-1 at the break. The right-hander lasted four innings and was charged with three runs and six hits. He struck out five and walked three.

It's the second time this season he's been bothered by blister symptoms, but he didn't skip a turn on the first occasion. Cueto, through a translator, said this ailment has never stuck him before this year and the cause could be the composition of the baseballs.

"I think so, probably," Cueto said. "I feel that the ball is tighter and with my three fingers I can't feel the ball.

"I think the best thing for me to do is to take some time off. Right now it feels bad. I'm not throwing very well and I don't want to hurt myself."

Clayton Richard (5-9) went 5 2/3 innings and surrendered four runs, 11 hits and two walks. Richard, who hasn't won in five starts in a row, struck out four.

"I thought he settled in relatively nicely there, until the sixth inning," Padres manager Andy Green said. "The sixth inning kind of got away from him."

It started with a leadoff walk to Hunter Pence which led to Richard's downfall.

"That's something I have control over and one of the things I could change," Richard said. "It's really difficult when you have the lead going and you're expected to come away on top and I wasn't able to do that."

The Giants regained the advantage with a two-run sixth as they chased Richard. Denard Span knocked in the go-ahead run with a single to score Joe Panik, who produced the second of consecutive singles against Richard.

In the fourth, San Diego took its first lead at 3-2 when Austin Hedges' single drove in Erick Aybar after his double to right.

The Padres tied it 2-2 in the second. Blash, who was recalled earlier from Triple-A El Paso, doubled in Cory Spangenberg after his inning-opening walk. Blash then scored on Aybar's single.

San Francisco went up 2-0 on Cueto's second-inning flare to right field, which brought in Brandon Crawford. After Crawford was safe at the plate, Hedges fired down to first base where Cueto was retired after rounding the bag aggressively.

The Giants struck in the first, taking a 1-0 lead on Posey's RBI single. Posey's hit fell just in front of a diving Blash in right field to bring around Brandon Belt after he reached on a two-out single.

NOTES: Giants INF Eduardo Nunez (hamstring) was activated off the disabled list and started at third base. ... OF Mac Williamson was optioned to Triple-A Sacramento. ... San Francisco RHP Mark Melancon (oblique) is playing catch, but only on flat ground. There's no timetable for his return. ... Padres OF Hunter Renfroe (neck), the team leader with 16 home runs, was put on the DL. ... RHP Jose Valdez was brought up from Triple-A. ... RHP Kirby Yates was placed on the paternity leave list.