Eric Hacker had plenty to show for his first start in the majors. About the only thing missing for the San Francisco right-hander was a victory.

Making a spot start after being called up from the minors earlier in the day in order to keep the rest of the Giants rotation on schedule, Hacker pitched well but got little support from San Francisco's defense and even less from the team's sputtering offense.

It all added up to another loss for the Giants — and a trip back down to the minors for Hacker.

"The experience is great," said Hacker, who pitched six strong innings in San Francisco's 5-3 loss to the San Diego Padres on Friday night. "They know what I do, they know what I bring to the table. Hopefully I'll get the opportunity again."

Hacker (0-1) allowed three runs on eight hits over six innings. He walked two, struck out seven and left with the Giants down by only a run.

Not too bad for a guy who before kicking off San Francisco's nine-game homestand had made only brief appearances in the big leagues, all of them in relief.

Against the Padres, Hacker gave up a home run to the first batter he faced then settled down to retire eight straight during one stretch. He ran into trouble in the fourth when he allowed two runs on four consecutive hits but got out of the jam by striking out Andy Parrino.

Hacker pitched out of trouble again in the sixth after loading the bases, getting Padres pitcher Cory Luebke to strike out swinging for the final out.

"He has a deliberate motion out of the windup and that caused a little bit of a timing problem the first time through the lineup," San Diego manager Bud Black said. "He pitched well, mixed his pitches. His slow breaking ball is tantalizing."

The Giants couldn't give Hacker enough run support, though, and lost for the third time in four games.

Afterward, the team announced Hacker was headed back to Triple-A Fresno and that right-hander Steve Edlefsen has been called up.

Nick Hundley matched his career high with four hits and drove in a run, while Chase Headley, Orlando Hudson and Cameron Maybin also drove in runs for the Padres, who won their second straight and fourth in six games.

Luebke (3-1) pitched six strong innings to win his third consecutive start. He gave up two runs on seven hits and struck out three. Four of the seven Padres' victories have come in his last four starts.

Huston Street pitched the ninth for his third save in as many chances.

Buster Posey hit a home run and drove in two runs for the Giants. Pablo Sandoval extended his hitting streak to 20 games with a third-inning single but San Francisco continued to struggle with runners in scoring position.

"We're kind of sputtering here," Bochy said. "We have to pick it up here offensively along with our defense. It's why we're .500. We're doing some good things but we're making some mistakes, too."

Hundley doubled home a run in the top of the first for the Padres and Angel Pagan led off the first with a home run for the Giants. Pagan, who has four career leadoff homers, hit a three-run homer in his last at-bat Thursday in Cincinnati.

Hudson and Maybin each delivered a two-out RBI single in the fourth to put the Padres ahead 3-1.

Posey's RBI double in the fifth pulled the Giants within 3-2 but the Padres added two more runs in the seventh against Jeremy Affeldt, one on a Headley single and the other on a wild pitch.

Posey hit his fourth home run of the season, a solo shot leading off the eighth.

Notes: Sandoval's hitting streak is the longest to start a season since Edgar Renteria hit in 23 straight for the Atlanta Braves in 2006. ... Hudson extended his hitting streak to 10 games. ... The Giants optioned RHP Dan Otero to Triple-A Fresno and transferred RHP Brian Wilson to the 60-day disabled list to make room for Hacker. ... RHP Anthony Bass (1-2, 2.33 ERA) starts for the Padres on Saturday. He has pitched 8 1-3 scoreless innings in four career appearances against the Giants. ... RHP Tim Lincecum (1-2, 8.20) looks to get his season untracked when he starts for the Giants on Saturday. He won four of five decisions against the Padres last year and has a career 1.96 ERA against them. ... Headley has hit safely in 16 of his last 18 games.