It was the 15th time that the Pirates have been shut out this season.
Correia tossed seven frames, allowing six hits and striking out five. He got the win, upping his record to 11-10.
"What I've seen is the steady improvement, I'm not going to say start-to-start," Padres manager Bud Black. "I mean, if you go month-to-month, I'll go even back to Spring Training, when we talked about the delivery and then early, we started talking about what I felt and he self-admitted it was the over-throwing of the fastball. Staying within his delivery, trying to stay on line, not spin off pitches and then it moved into incorporating the curveball and the changeup more. You saw that [in] June and July and then I think here in August and September, I think you've seen the culmination of all those things coming together. Any pitcher will tell you that he wants to improve, but he's made great strides."
Correia was pleased with his outing.
"I threw a lot of strikes," Correia said. "I went deep in some counts early, which got my pitch count up and I was just happy to get some quick outs after that and be able to stay in the game a long time."
When injuries hit the Padres pitching staff early this season, Correia stepped into the breach and has developed into the ace of the staff, a role he accepts.
"It is what it is," Correia said. "Now I'm the guy with the most experience and I'm the only guy that's been in there all year. I don't think it was a position the Padres wanted to be in, but I think it is what it is right now and I'm happy to be out there and getting us some wins."
Pirates lefty Paul Maholm absorbed the loss, falling to 8-9 on the season. He pitched six innings and gave up three runs, two of them earned. He allowed nine hits and recorded three strikeouts.
The Padres had two prime scoring opportunities snuffed out by the Pirates in the second inning. Oscar Salazar led off with a double, but was gunned down at home plate by Pirates center fielder Andrew McCutchen following a single by Edgar Gonzalez. Correia was robbed of an RBI single by Pirates shortstop Ronny Cedeno, who made a diving stop behind second and threw out Correia.
San Diego broke through against Maholm in the third inning. Everth Cabrera singled and advanced to third on a ground-rule double to left by David Eckstein. Cabrera scored on a sacrifice fly by Adrian Gonzalez. With the bases loaded, Chase Headley, who had walked, scored when Edgar Gonzalez hit a ground ball to Pirates third baseman Neil Walker, who threw home for a forceout. Pirates catcher Ryan Doumit uncorked a wild throw to first, allowing Headley to score, giving the Padres a 2-0 lead.
The Padres nicked Maholm again in the top of the fifth inning. Headley doubled and scored on a ground-rule double by Salazar, increasing the Padres lead to 3-0.
San Diego manufactured its fourth run in the ninth inning. Pinch-hitter Luis Durango drew a walk off Pirates reliever Steven Jackson. Durango stole second base and advanced to third on an errant throw by Doumit. Durango scampered home on a sacrifice fly by Cabrera.
"We had a good second inning," Black said. "We got our hits against him. I've always liked Maholm, but I thought as a group throughout the lineup, we were on and everybody was bearing down and having good at-bats and our pitchers made it hold up."
Padres right-hander Luke Gregerson ran his consecutive scoreless innings streak to 18 with his strong eighth inning.
San Diego right-hander Sean Gallagher came on to pitch the ninth inning, but ran into trouble and was lifted with one out and runners on first and second. Padres closer Heath Bell struck out the two hitters he faced to record his 39th save.
George Von Benko is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.