PITTSBURGH -- Joe Maddon believes his young Chicago Cubs showed their postseason worthiness Wednesday night.

First baseman Anthony Rizzo's sacrifice fly in the top of the 12th inning lifted the Cubs to a 3-2 victory over the Pittsburgh Pirates on Wednesday night and edged them closer to the first National League wild-card spot and their first postseason berth since 2008.

"One of the things I've always used as a benchmark is an extra-inning win on the road," said Maddon, in his first season at Cubs' manager. "That's not easy to do under these circumstances, in this place at this time of the year. I'm really proud of our efforts."

With the scored tied at 2, left fielder Chris Denorfia led off the winning rally with a single off reliever Vance Worley, and Quintin Berry pinch ran for him. Berry took second on a wild pitch, moved to third on center fielder Austin Jackson's single and scored when left fielder Starling Marte made a sliding catch of Rizzo's fly ball.

Closer Hector Rondon (6-4) pitched two scoreless innings for the win.

Worley (4-6), the eighth Pirates' pitcher, entered at the start of the 12th.

The Cubs (84-61) drew within three games of the Pirates (87-58) for the first wild-card spot after winning for the second time in three games in the four-game series that concludes Thursday afternoon. Chicago holds a commanding eight-game lead for the second wild-card berth over the San Francisco Giants, pending the result of the Giants' game against the Cincinnati Reds later Wednesday night.

"You don't want to think about the playoffs too much yet but if we keep winning games like this then I really like our chances of getting there," Cubs second baseman Starlin Castro said.

The Pirates dropped four games behind the first-place St. Louis Cardinals (91-54), who won 5-4 at Milwaukee, in the NL Central while the Cubs stayed seven games back.

Given a 2-0 lead going into the seventh inning, Cubs right-hander Jake Arrieta was unable to hold it in his attempt to become the first major-league pitcher to 20 wins this season.

Arrieta allowed a run to score in the seventh when he threw away Marte's comebacker with two outs for an error.

The Pirates tied it in the eighth when pinch runner Sean Rodriguez scored from third as right fielder Gregory Polanco grounded into an inning-ending reverse 4-3-4-2-5 double play with the bases loaded.

"We won the game and that's obviously the most important aspect but that throw was unacceptable on my part," Arrieta said. "That's going to stay with me for a while because that's how I am personally. I made a good pitch on Marte and then I could have cost us the ballgame with that throw to first base."

Arrieta wound up allowing two runs -- one earned -- and six hits in eight innings while striking out five and walking one.

Arrieta was attempting to become the first Cubs pitcher to win 20 games since 2001, when Jon Lieber went 20-6. Arrieta also had his eight-start winning streak snapped, the longest by a Cubs pitcher since Milt Pappas won 11 in a row in 1972.

"He pitched beautifully once again," Maddon said. "He was outstanding."

Cubs third baseman Kris Bryant had three hits and catcher Miguel Montero added two. Bryant was a combined 0-for-7 with five strikeouts Tuesday when Chicago split a doubleheader with the Pirates.

Marte and second baseman Neil Walker had two hits each for the Pirates.

"It was a fun game," Pirates shortstop Jordy Mercer said. "We showed some resilience. We continued to fight and that's what a lot of us are proud about. We gave us a chance to win at the end and against a pitcher like (Arrieta), that's all you can ask for."

Pirates right-hander A.J. Burnett (8-6) pitched into the sixth inning in his second start since being activated from the disabled list. He was sidelined from July 31 to Sept. 9 with a strained flexor tendon in his left elbow. He gave up two runs and eight hits in 5 1/3 innings with seven strikeouts and one walk.

Burnett took a shutout into the sixth inning before the Cubs scored twice on an RBI double by Bryant and a squeeze bunt by Castro.

NOTES: Cubs RF Jorge Soler will be activated from the disabled list once Class A Myrtle Beach is finished with the Carolina League playoffs, which are scheduled to last until no later than Friday. Soler is on a rehab assignment and has been out since Aug. 24. ... Cubs RHP Jason Motte (right shoulder sprain), also on the DL since Aug 24, has started throwing off flat ground. ... Pirates 3B Aramis Ramirez started at first base in place of 1B Pedro Alvarez for the fourth time in nine games after having never played the position in his 18-year career prior to Sept. 8. ... The four-game series ends Thursday afternoon with Chicago RHP Kyle Hendricks (7-6, 4.08 ERA) facing Pittsburgh RHP Charlie Morton (9-7, 4.02 ERA).