CHICAGO -- Dioner Navarro welcomes the chance to come off the bench to hit in a big spot late in the game.
"Ninety percent of the time when you pinch-hit in key situations, I don't want to sound cocky, but I kind of like to be in that situation," Navarro said. "It's the best against me and I love the challenge every time I get the opportunity."
Navarro is 6 for 14 as a pinch hitter this season with two home runs and four RBI.
"Navarro has been doing it all year, constantly off the bench and getting the job done," Cubs manager Dale Sveum said. "It's a nice asset to have. Our bench has done a good job all year."
Anthony Rizzo sparked the winning rally with a leadoff single. He advanced on Alfonso Soriano's single and went to third when Pirates catcher Russell Martin threw the ball into center field while trying to pick Rizzo off second.
"We know we have a better team than the record shows," Cubs starter Carlos Villanueva said. "We've lost some heartbreaking close games. You take back at least half of those games and we're in a better position. Right now, I think it's important for us to keep playing well into the All-Star break and have a strong second half."
"We were one strike away there," Gregg said. "I made some good pitches in to [Marte], made him conscious of the ball in. I felt like I made a pretty good pitch away from him and he did a good job of hitting and going to get it."
Chicago (38-48) improved to 20-18 since it got off to a lackluster start. It has won five of its last seven series.
"To win two out of three, it was nice beating the best team in baseball," Sveum said.
Pittsburgh (53-34) has dropped three of four to fall into a tie with St. Louis for the NL Central lead and the best record in the majors.
"What hurt us earlier was the fourth and sixth innings with a runner at third and we weren't able to score them," Pirates manager Clint Hurdle said. "But we continued to play hard, we continued to battle. We get to the ninth inning with two outs and two strike and Marte rides a ball out of the ballpark. These games just battle-test you."
"I was happy to contribute today and it was nice getting the win," Hairston said. "Navarro came off the bench after waiting four hours, came up huge for us, and throughout the year we're going to remember this and build on it. To win two out of three against a team like Pittsburgh, you have to feel good about that."
Pirates right-hander A.J. Burnett came off the 15-day disabled list after being sidelined by a strained right calf and pitched five solid innings. He allowed two runs, one earned, and three hits.
Villanueva (2-4) lasted only four innings, by design. He was making his first start since Scott Feldman was traded to Baltimore, opening a spot in the rotation, and Sveum said before the game he likely would keep Villanueva to a 75-pitch count.
Villanueva allowed one run and three hits while throwing 69 pitches. He struck out five and walked one.
"Winning the series against these guys, they're in first place, and the last couple of series we've won, so I think that definitely cures a lot of aches and pains and everybody is happy," Villanueva said.
Villanueva also helped himself in the third with a broken-bat leadoff single. He moved to third on Starlin Castro's one-out double and scored on an error by first baseman Garrett Jones. Alfonso Soriano's sacrifice fly drove in Castro, who moved to third on Jones' error.
Burnett returned the favor in the fifth. He led off with a single and was erased on a fielder's choice by Marte. But Jose Tabata followed with a double to deep left that tied it at 2.
Tabata also doubled and scored on Andrew McCutchen's double in the fourth.
- Cubs OF Brian Bogusevic, who was called up from Triple-A Iowa on June 25, remains day to day with hamstring tightness. He hit for Villanueva in the fourth and struck out.
- The Cubs make up a rainout with the crosstown White Sox on Monday at U.S. Cellular Field. Cubs RHP Matt Garza (4-1, 3.45 ERA) faces White Sox LHP Hector Santiago (3-5, 3.50 ERA).
- The Cubs wrap up this season's interleague slate with a two-game series against the visiting Los Angeles Angels on Tuesday and Wednesday.
- RHP Ryan Reid was optioned to Triple-A Indianapolis to make room for Burnett.
- The Pirates start a six-game homestand Monday that includes three-game series vs. Oakland and the Mets. Monday's game features a pair of All-Star pitcher, with Jeff Locke (8-1, 2.12 ERA) facing the A's Bartolo Colon (11-3, 2.78 ERA).