CHICAGO -- A.J. Burnett carried a shutout into the ninth inning, and Pedro Alvarez hit a home run to lead the Pittsburgh Pirates to a 6-2 victory over Jeff Samardzija and the Chicago Cubs on Saturday at Wrigley Field.
Alvarez, who also had a run-scoring single, hit a two-run home run in the fourth for Pittsburgh, which can sweep the three-game series Sunday. The Pirates won Friday's opener, 2-0.
Burnett (4-6) continued to pitch well at Wrigley Field against the Cubs, giving up two runs and four hits and striking out five in 8 1-3 innings to earn his first victory since May 3 at Washington.
Entering Saturday, Burnett was 4-0 with a 3.09 ERA lifetime at Wrigley and 6-2 with a 3.21 ERA lifetime against the Cubs.
Alfonso Soriano's two-run home run with one out in the ninth broke up the shutout and ended the day for Burnett, who was relieved by Tony Watson.
Russell Martin's two-run home run in the eighth to give the Pirates a 6-0 lead was the 100th of his career.
The Cubs have lost five of six since winning a season-high five straight.
Chicago didn't get a hit against Burnett until the fifth, when Nate Schierholtz led off with a double.
In his previous start at Wrigley on July 31 of last year, Burnett took a no-hitter into the bottom of the eighth, eventually giving up his first hit with two out in the inning.
Samardzija, meanwhile, was 4-1 with a 0.98 ERA in 15 games during his career against Pittsburgh, but struggled Saturday and took the loss.
Samardzija (3-7) pitched six innings, allowing four runs and eight hits. The eight Pirate hits matched the most given up this season by Samardzija, equaling his start May 10 at Washington.
The offense was welcome for the Pirates, who had scored eight runs over their previous four games.
Alvarez singled in the second to drive in Garrett Jones to open the scoring and give Pittsburgh a 1-0 lead. After allowing Neil Walker's single, Samardzija got out of the inning when Clint Barmes grounded into a double play.
Pittsburgh took a 2-0 lead in the third off Samardzija on Travis Snider's single to center, scoring Starling Marte, who had singled with one out and stolen second.
Marte went 1-for-2 on stolen-base attempts, giving him 16 on the season.
In the fourth, Alvarez gave the Pirates a 4-0 lead in the fourth on a two-run home run off Samardzija, bringing in Martin. The home run was his 13th of the season.
The Pirates' third baseman also contributed in the field.
Chicago had its first chance off Burnett in the sixth with runners and second and third and two out, but Alvarez made a diving play on Soriano's grounder, getting the Cubs left fielder on a throw across the diamond.
Soriano's home run in the ninth was the 379th of his career, tying Orlando Cepeda and Tony Perez for 64th all-time.
NOTES: Gerrit Cole, the No. 1 overall pick in the 2011 draft, will make his debut Tuesday for the Pirates against the Giants. ... The Cubs said reliever Kyuji Fujikawa will visit Dr. James Andrews on Monday and is expected to have Tommy John surgery on his right elbow on Tuesday. ... Pittsburgh right-hander Jeff Karstens, who hasn't pitched this season, on Friday underwent surgery on his right rotator cuff and labrum. Karstens will be shut down for 10-to-12 weeks. ... Cubs manager Dale Sveum said it's "getting closer" to giving struggling shortstop Starlin Castro a day off. Castro went 0-for-3 on Saturday and is in a 3-for-34 skid. ... The Pirates placed pitcher Jared Hughes on the 15-day disabled list retroactive to Friday because of right shoulder inflammation, and recalled outfielder Alex Presley from Triple-A Indianapolis. ... Pirates manager Clint Hurdle said pitcher Jose Contreras will throw one inning on a rehab assignment Monday, probably for Indianapolis, while Wandy Rodriguez is expected to throw a side session Monday and Jeanmar Gomez will do the same, and could go on a rehab assignment Thursday if "that goes well." ... On Sunday, the Pirates' Jeff Locke (5-1, 2.45) will face Chicago's Edwin Jackson (1-8, 6.29).