PITTSBURGH — Nick Castellanos hit a two-run double, Jake Cronenworth added a two-run homer and the San Diego Padres beat the Pittsburgh Pirates 8-2 on Wednesday.

Castellanos’ double began a four-run seventh inning that broke open a scoreless game and helped San Diego clinch the three-game series.

Michael King (1-1) allowed two runs on four hits over six innings while striking out four and walking three for San Diego. Justin Lawrence (0-1) took the loss after giving up four runs on three hits in one inning for Pittsburgh.

The game remained scoreless through six innings as Mitch Keller and King matched each other early. Keller worked six scoreless frames, allowing three hits and striking out four, while King limited Pittsburgh to two hits through the first six innings.

“I feel really good. It was a quick one,” Keller said. “It felt like [I was pitching] quick innings there, pitch count was down. That’s the goal every time to be efficient and just to give yourself the opportunity to go seven, eight, or whatever it may be here later in the season.”

San Diego broke through in the seventh after Xander Bogaerts reached on a throwing error and Miguel Andujar doubled to put runners at second and third. Castellanos followed with a double to left field that scored both runners and gave the Padres a 2-0 lead.

Luis Campusano grounded out before Cronenworth lined a two-run homer to right-center field, stretching the lead to 4-0.

“I thought Mitch threw the ball extremely well,” Pirates manager Don Kelly said. “He was really efficient early on, and kept them off balance with a bunch of pitches. He was in the zone with his fastball, and mixing in the changeup, as well. It was pretty effective.”

Pittsburgh answered in the bottom half. Nick Yorke singled and Nick Gonzales doubled to start the inning before Konnor Griffin hit a sacrifice fly to score Yorke. Joey Bart later added an RBI single that cut the deficit to 4-2.

The Padres pulled away in the ninth, though, as Campusano doubled home Bryce Johnson. Fernando Tatis Jr. added an RBI single and Jackson Merrill drove in a run on a fielder’s choice before Merrill stole second and Tatis stole home to make it 8-2.

Kyle Hart and Jeremiah Estrada each worked scoreless relief innings before Mason Miller struck out two in a perfect ninth. Miller extended the longest active scoreless streak in the majors to 26ª innings.

On deck

Tonight: Idle

Next up: Pittsburgh at Chicago Cubs, Friday, 2:20 p.m.

Pitching matchup: Bucs RHP Carmen Mlodzinski vs. Cubs LHP Shota Imanaga

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TV: SportsNet Pittsburgh