Updated

On the surface, it looks as though a series victory is simply on the line Sunday afternoon between the Cincinnati Reds and Pittsburgh Pirates in the rubber match of a three-game set.

But it goes deeper than that.

The two current NL wild card holders will meet again in Cincinnati next weekend to wrap the regular season and a tad bit more could be at stake by then.

Only the Washington Nationals are challenging the Pirates and Reds in the wild card race, but the two postseason hopefuls would love to avoid the tense one- game playoff between wild card winners. So while Cincinnati and Pittsburgh slug it out for potential home-field advantage for the play-in game, both are also looking to keep pace with the NL Central-leading St. Louis Cardinals.

The Pirates rode A.J. Burnett's arm to a 4-2 victory on Saturday after blowing a late lead to lose Friday's opener in extra innings. Pittsburgh moved a game ahead of Cincinnati in the standings and remained two games back of St. Louis.

The victory also gave Pittsburgh an outside shot of wrapping up a playoff spot today for the first time since 1992. The Pirates need a victory as well as a pair of losses in today's doubleheader for the Nationals, who are 4 1/2 games back of a wild card spot, against the Miami Marlins.

Burnett struck out 12 batters last night for the first time since Aug. 27, 2009 with the New York Yankees. He gave up two runs, four hits and three walks over seven innings, surpassing 200 strikeouts in the season.

"I was just focused, I was locked in," Burnett said.

Russell Martin hit a two-run homer for the Pirates, who had lost four of five coming in.

A night after Cincinnati scored three runs in the ninth inning and won the opener of the three-game series 6-5 in 10 innings, the Pirates made sure it didn't happen again by turning key double plays in the last two innings.

Jason Grilli, who had 30 saves before going on the disabled list July 23 with a strained forearm, replaced Mark Melancon as the closer and picked up his first save since July 21. Melancon was charged with a blown save in Friday's loss.

Zack Cozart hit a solo homer but the Reds had a four-game winning streak snapped. Homer Bailey allowed four runs -- two earned -- in 5 2/3 innings to suffer the loss.

"We just couldn't get much going against (Burnett). We got some runs early, then he settled down," Reds manager Dusty Baker said.

The Pirates own a slim 8-7 lead in the season series and will visit the Chicago Cubs before going to Cincinnati next weekend. The Reds begin their season-ending homestand on Monday versus the New York Mets.

The Reds hope to have Shin-Soo Choo back by then. He sat out last night's loss with a jammed left thumb suffered on a headfirst slide the previous night. It is possible Cincinnati's leadoff hitter misses a few games with the ailment.

Choo has hit 21 homers this year with an on-base percentage of .423.

The Reds turn to Bronson Arroyo, who is 0-2 in four starts since winning four straight outings.

Arroyo, though, has not allowed more than two earned runs in three straight games and is coming off a no-decision versus Milwaukee last Sunday. The righty was charged with two runs on three hits and four walks over 6 1/3 innings, denied the win as the bullpen allowed four runs over the final two frames in defeat.

"That's probably as crushing of a defeat as we've had all year," said Arroyo, who is 13-11 with a 3.56 earned run average in 30 starts this year.

Arroyo has faced the Pirates only once so far in 2013, getting a no-decision at home on June 19 despite seven innings of one-run ball. The 36-year-old is 6-7 against the club lifetime with a 3.70 ERA.

The struggling Jeff Locke gets the start today for the Pirates and will try to get on track against a club he has performed well against over his brief career. He is 2-0 versus the Reds in four starts with a 1.19 ERA.

Locke, however, has won just once over his last 10 starts and is coming off a 5-2 setback to San Diego on Tuesday. The 25-year-old southpaw was charged with four runs on seven hits and three walks over five innings of work.

Locke, an All-Star this year, fell to 10-6 with a 3.27 ERA in 29 starts this season.