PITTSBURGH -- Pinch-runner Quintin Berry raced home onAnthony Rizzo's sacrifice fly in the top of the 12th inning, and the Chicago Cubs slipped by the Pittsburgh Pirates 3-2 on Wednesday night.
Chicago starter Jake Arrieta's bid to become the first 20-game winner in the majors went along smoothly before he wavered in the eighth as Pittsburgh rallied to tie it. Arrieta allowed two runs, one earned, and six hits but failed to pick up a win for the first time since Aug. 4.
Chris Denorfia singled off Vance Worley (4-6) to start the 12th and was replaced by Berry, who advanced to second on a wild pitch and third on Austin Jackson's single. Starling Marte tracked down Rizzo's sinking liner to left field but had no shot at Berry.
Hector Rondon (6-4) worked two innings as Chicago pulled within three games of the Pirates for the top spot in the NL wild-card race.
Neil Walker and Marte had two hits apiece for Pittsburgh, which fell four games behind first-place St. Louis in the NL Central.
Arrieta's rise is one of the main reasons the Cubs are closing in on their first playoff berth since 2008. His 19 wins are two more than he managed from 2012-14 combined, when the right-hander struggled with his command and an identity on the mound.
That's not an issue anymore.
The Pirates, trying to chase down front-running St. Louis and avoid playing in a third straight wild-card game, didn't exactly do anything to build much confidence should they face the Cubs in the one-game elimination on Oct. 7.
Chicago appeared to give Arrieta all the offense he would need in the sixth when the Cubs finally got to Pittsburgh starter A.J. Burnett. The 38-year-old matched Arrieta for five scoreless innings in his second start since a six-week stay on the disabled list with a strained right elbow.
Rizzo singled in the sixth and scored on a double by Kris Bryant. The rookie slugger made it 2-0 when he raced home from third on a sacrifice bunt back to the mound by Starlin Castro, who reached safely when reliever Jared Hughesthrew wide of first for an error.
Burnett gave up two runs and eight hits in 5 1-3 innings. He walked one and struck out seven to give him 2,495 strikeouts in his 17-year career.
Hughes escaped without further damage and Pittsburgh used a rare mistake by Arrieta to draw closer. Gregory Polanco singled in the sixth with two outs, stole second and scored when Arrieta flipped high to Rizzo at first for an error on a routine chopper by Marte.
Then things got weird. Neil Walker led off the eighth with a single and pinch-runner Pedro Florimon raced to third when Francisco Cervelli's sharp liner glanced off shortstop Javier Baez's glove and into shallow right. Florimon was out at home on a grounder to Baez, with replay officials ruling catcher Miguel Montero did not block the plate.
Pittsburgh managed to tie it anyway. Arrieta walked pinch-hitter Pedro Alvarez to load the bases, and Chicago manager Joe Maddon decided to keep his ace in even with his pitch count at 116. Polanco grounded to second, but rather than go to second for the forceout, Castro hesitated and went to first instead, giving pinch-runner Sean Rodriguez time to cross the plate safely before a double play was completed with several throws.
The baseball home of Hall of Fame right fielder Roberto Clemente pulled out all the stops during the day Major League Baseball set aside in his honor. The Pirates had Clemente's No. 21 painted on the grass in front of the 21-foot high Clemente Wall in right. The Pirates handed out the team's Roberto Clemente Award - given out by each major league club to a player who exemplifies skill on the field and community involvement off it - to center fielder Andrew McCutchen.
Clemente died on New Year's Eve 1972 when a plane carrying humanitarian aid to earthquake-ravaged Nicaragua crashed. His widow Vera and sons Roberto Jr., Ricky and Luis threw out the first pitch.
Cubs: RHP Kyle Hendricks (7-6, 4.08 ERA) starts the series finale. He is 0-1 with a 5.63 ERA in three career starts against the Pirates.
Pirates: Charlie Morton will try to win 10 games for the second time in his career when he makes his 21st start of the season Thursday. Morton (9-7, 4.02) is 6-2 with a 3.00 ERA in 10 games at PNC Park this year.