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Erratic lefty Jonathan Sanchez will try to clinch a series win for the Pittsburgh Pirates on Sunday when they host the suddenly slumping Atlanta Braves to close out a four-game series at PNC Park.

The Braves won 10 straight games into the middle portion of this week, but have since dropped three of four - including two straight to Pittsburgh.

The Pirates pulled ahead in the series on Saturday, when Gaby Sanchez stroked a go-ahead two-run homer and James McDonald spun six innings of one-run ball in a 3-1 triumph.

Andrew McCutchen went 2-for-4 with a pair of doubles and an RBI and Jason Grilli struck out the side in the ninth to record his sixth save and preserve the win.

McDonald (2-2) was a bit unsettled early, but settled down and finished with nine strikeouts. He allowed just two hits and walked four.

"I felt confident in everything I did," said McDonald. "No negative thoughts entered my mind tonight."

The Pirates were able to knock former draft pick Paul Maholm (3-1) from the ranks of the unbeaten. Maholm had not allowed a run in his first three starts, but surrendered three in the sixth to absorb the loss.

The Braves were 0-for-6 with runners in scoring position and managed just four hits.

Jonathan Sanchez, a 13-game winner with the San Francisco Giants in 2010, has won just five times in 36 big-league appearances since, including two straight subpar starts with the Pirates, who he signed with in the offseason.

He made his Pittsburgh debut with five innings of six-hit, three-run ball in a 3-0 loss to the Los Angeles Dodgers on April 5, then followed it up when he surrendered nine runs in 3 1/3 innings of a 10-2 rout at Arizona on April 10.

He's 1-3 in nine career games - including seven starts - against Atlanta, while allowing 21 runs in 34 2/3 innings.

Sanchez has split two career decisions at PNC Park with a 5.91 ERA.

Atlanta goes with righty Kris Medlen, who aims for a third straight quality start.

The 27-year-old, who was 10-1 a year ago, opened this season with a five- inning effort in a 2-0 loss at Philadelphia on April 4, then bounced back five days later to win at Miami, 3-2.

He turned in a quality start, but got a no-decision, while allowing an earned run on six hits in seven innings of the Braves' 6-3 defeat of Kansas City on April 16.

He's 2-0 in four career meetings with the Pirates while posting a 2.55 ERA across 17 2/3 innings.

Medlen's one career start at PNC Park yielded a no-decision after he gave up two runs on seven hits in 5 2/3 innings.

The Pirates won four of seven games between the teams in 2012, while the Braves took four of six in 2011.