SAN DIEGO -- Drew Pomeranz left a first impression that caused some to do a double-take.

Yep, he was that good.

Pomeranz stymied Pittsburgh over 6 2/3 innings and the San Diego Padres won for the third time in four games, defeating the Pirates 8-2 on Wednesday night.

The left-handed Pomeranz made his Petco Park debut as a Padre and didn't disappoint. Mixing his fastball and curve, Pomeranz, a former first-round pick, had the Pirates baffled for most of his appearance. Pittsburgh had just two runners reach scoring position, one each in the first and seventh innings.

Pomeranz (2-1), who came to San Diego in an offseason trade with the Oakland A's, allowed an unearned run on four hits as the Padres clinched their first home series win of the season. He struck out a career-best 10 batters and walked three while throwing a season-high 111 pitches.

"My curveball was the best thing working today," Pomeranz said. "I threw a lot of them. I was attacking them with it early on and they kept missing it, so I just kept throwing it."

It was the Pirates' first look at a southpaw starter, the final major team to do so.

"He had big-time curveball tonight and you don't see that every day," Pirates manager Clint Hurdle said. "We didn't see anybody in spring training that matched up with that curveball. He just had an exceptional curveball."

San Diego shellacked Pirates starter Jeff Locke (0-2) for eight runs between the second and fourth innings.

The Padres defense also excelled -- save an error by Alexei Ramirez -- with stellar plays by infielders Jemile Weeks and Adam Rosales. Melvin Upton Jr. also robbed Matt Joyce of a ninth-inning, two-run homer with a catch above the left-field fence.

Matt Kemp, who also singled, smacked his team-leading fifth home run and Ramirez had two RBIs and two hits to pace San Diego. John Jay and Derek Norris also had two hits.

After the Padres stumbled from the gate by getting swept by the Los Angeles Dodgers and losing seven of their first 10 games, Kemp senses a change in momentum.

"I think everything was solid," Kemp said. "We've had a couple of good wins but I think this by far was the best one we've had. We need to have more of those. That would be nice."

Jordy Mercer had three hits for the Pirates.

After being shut out their first three games at Petco, the Padres have hit four home runs in their past two contests against the Pirates.

Kevin Quackenbush and Luis Perdomo relieved Pomeranz.

Pomeranz gave up three hits and walked three over the opening five scoreless innings, setting a career high with nine strikeouts in that span.

Locke was chased in the fourth before retiring a batter. He surrendered a solo homer to Kemp, which put the Padres ahead 8-0, and registered his fourth walk, this one to Upton Jr., before exiting.

"He has got to keep working," Hurdle said of Locke. "He can't look at this as anything other than a challenge."

In falling to 1-10 against NL West teams and 0-3 to the Padres, Locke was charged with eight runs on 11 hits with four walks.

San Diego scored three times in the third inning to forge ahead 7-0. The big blows were an RBI triple by Ramirez, a run-scoring single by Rosales and a Pomeranz single for his first RBI on the season.

The Padres struck first with a four-run second, when Locke's command issues -- he had a career-high seven walks in his previous start -- came back to haunt him as San Diego batted around in a 40-pitch inning.

Upton led off with a free pass and advanced to second on Norris' infield single. Ramirez chased in Upton with a sharp single to center for a 1-0 lead. Rosales drew another walk, which preceded Weeks' RBI single to make it 2-0. A one-out infield hit by Jay scored Ramirez for a 3-0 edge, then Wil Myers' infield single sent home Rosales.

"A couple inches this way or that way and we make plays," Locke said. "It was a kind of hit 'em where they ain't thing. There were some walks in there, too, of course, but to be honest no matter how it looks there's not much you can change about it. You have to make sure those balls on the ground find some gloves."

NOTES: Pirates manager Clint Hurdle said Chris Stewart will catch LHP Gerrit Cole in Thursday's series finale. ... C Francisco Cervelli could see additional playing time at first base. ... Last season, Pittsburgh was 20-16 against opposing lefties. ... Padres 2B Cory Spangenberg (quad) was placed on the DL. ... RHP Tyson Ross (shoulder) was shut down after experiencing discomfort in Tuesday's abbreviated throwing session. He will undergo an MRI. ... INF Jemile Weeks was called up from Triple-A El Paso.