Veteran righty A.J. Burnett tries to stay unbeaten for his career against the Chicago Cubs Friday when the Pittsburgh Pirates host them in the opener of a three-game series at PNC Park.

Burnett, a 35-year-old Arkansas native, is 6-0 in seven lifetime starts against the Cubs with a 2.78 earned run average across 45 1/3 innings of work. He tossed a nine-inning gem in Chicago when the teams last met on July 31 at Wrigley Field, allowing a single hit and striking out eight batters in a 5-0 victory.

Burnett beat the Cincinnati Reds in a subsequent start on Aug. 5, but has won just once in five starts since, downing the Los Angeles Dodgers on Aug. 16 while losing twice to San Diego and St. Louis while getting no-decisions in starts against the Padres and Milwaukee.

The Pirates have lost four of his last five starts after going 17-3 in his first 20. As a result. Pittsburgh has slipped off the pace in the National League's Central Division race, which they trailed by 10 games heading into Thursday. The Pirates are 1 1/2 games behind Los Angeles for the second of the league's two wild card berths.

The Cubs oppose Burnett with lefty Travis Wood, who seeks his first victory in more than two months.

The 25-year-old, also from Arkansas, was 4-3 on the season after a six-inning stint on July 6 that yielded an 8-7 win over the New York Mets. He's not won since, however, instead dropping eight decisions over 10 starts in which the Cubs are also winless at 0-10.

Wood's ERA, which was 3.05 after the victory in New York, has soared to 4.64, though he's still allowed fewer hits (110) than innings pitched (120 1/3) and is limiting opposing batters to a .244 average - nearly 50 points lower than the .293 clip he allowed over 106 innings with the Reds last season.

Wood last faced the Pirates on Aug. 1 and took an 8-4 loss after allowing two runs on three hits in five innings, with three walks and six strikeouts.

On Thursday in Washington, Kurt Suzuki hit the go-ahead three-run home run in the second inning, as the Nationals finished off a sweep of the Cubs with a testy 9-2 victory in the finale of a four-game series.

Anthony Rizzo collected three hits, including a solo homer, for the Cubs, losers in six straight and nine of 11.

Justin Germano (2-6) was tagged in defeat for seven hits and seven runs - six earned - over four full frames.

On Wednesday in Pittsburgh, Kevin Correia tossed six solid innings and Brock Holt knocked in a pair of runs to lead the Pirates past the Houston Astros, 6-3, in the rubber match of a three-game series.

Correia (10-8), who got the start in place of an injured Jeff Karstens, allowed one run on four hits and a walk for his first win since Aug. 8. He was making his sixth appearance and third start since his last victory.

Alex Presley added two hits, an RBI and three runs scored for the Pirates, who won their second straight following a four-game slide.

"I thought it was a very efficient offense tonight. We were able to score some runs different ways. The guys gave us some good at-bats," Pirates manager Clint Hurdle said.

The Pirates won six of the first nine games between the teams this season, including two of three in a series at Wrigley Field from July 30-Aug. 1. The teams split 16 games in 2011.