PITTSBURGH -- After Francisco Liriano set the stage with a near history-making performance, pinch-hitter Justin Morneau delivered an eighth-inning RBI single, lifting the Pirates to a 3-2 victory over the Cubs on Sunday in front of a crowd of 36,559 at PNC Park, the 20th sellout of the season setting a club record.

With one out in the eighth, Andrew McCutchen was hit by a pitch and Marlon Byrd singled. Morneau singled to left off Cubs reliever Pedro Strop, plating McCutchen and breaking the 2-2 tie.

It was Morneau's first RBI since he was acquired from the Twins on Aug. 31. He and fellow newcomer Byrd -- who was acquired from the Mets on Aug. 27 and hit the decisive homer in Saturday night's win over the Cubs -- have sparked the Bucs.

"They've impacted the club, they've impacted the lineup and everything we're doing," Pirates manager Clint Hurdle said. "We had a good team coming in to that point when the deals were made, and we just made a good team stronger."

"I think that's the key to winning teams," Morneau said. "It seems like it's somebody different every day, and obviously starting pitching is the first thing, and those guys have given us a chance pretty much every night. You like to be able to come through for those guys when they throw the ball so well. It's unfortunate Liriano doesn't get the win, but the team gets the win, and that's the most important thing, and it's fun to be a part of that."

The Pirates have won two in a row and took three games in the four-game series. They remained tied atop the National League Central with St. Louis, which defeated Seattle on Sunday, and upped their lead to 3 1/2 games over the Reds, who fell to the Brewers. The Bucs also reduced their magic number for clinching a playoff berth to six.

Liriano carried a no-hitter into the seventh inning, but his pitch count stood at 99, and he had issued four walks. Junior Lake broke up the no-hitter with a leadoff infield single to deep short, and Liriano lost the lead on a two-run home run by Welington Castillo. Right-hander Bryan Morris came on and closed out the inning.

"He was very dominant," catcher Tony Sanchez said. "The fastball command was better than it was in Texas, so it allowed us to keep them guessing, it allowed us to speed them up and then slow them down with the offspeed stuff. We stuck to our strengths and used his slider and his changeup a lot, which got us a lot of outs early in the counts."

Liriano has a history of dominating the Cubs. Entering Sunday's game, he was 3-1 with a 1.88 ERA in four career starts against them. That includes a complete-game victory on July 5.

"He's pitched outstanding against that ball team," Hurdle said. "He was on the edges and then just off of them. The pitch count got probably a little higher than he wanted it to, but he was able to get outs, he had a no-hitter through six innings. Four walks complicated some things, four strikeouts. He battled because he competes and finally got a no-decision in his 24th start."

Liriano tossed six-plus innings and gave up two runs on three hits. He received a no-decision, after factoring into the deicision in all 23 of his previous starts. While pitching for the Twins, Liriano tossed a no-hitter in a 1-0 win vs. the White Sox on May 3, 2011. He tossed 123 pitches in that game, walking six and striking out two.

"I looked up on the scoreboard in the sixth inning, and it said 92 pitches," Sanchez said. "Usually around a hundred pitches is when Frankie starts to tire out. We were going to try and get him through as many innings as possible with as little amount of pitches as possible. We got through the sixth. We left a pitch out over the plate, and Castillo hammered it."

"Liriano's not easy to hit," Castillo said. "He's got good offspeed [stuff], and he throws it for strikes. He's a guy you have to be aggressive against all the time, because he can throw 96 [mph] and 88, and a slider 85, 87. What makes him good is they all look the same. His changeup looks like his fastball, his slider looks like his fastball. He's been good his whole career. The approach we had to take was [to] be aggressive and try to get him early."

Cubs starter Travis Wood worked six innings and allowed two runs on five hits.

The Pirates staked Liriano to a 1-0 lead in the first inning. Jose Tabata led off with a triple and scampered home on a wild pitch by Wood.

The Bucs added a run to make it 2-0 in the fourth inning on Sanchez's solo home run, his second of the season.

Right-hander Kyle Farnsworth pitched a scoreless eighth inning and got his first win with the Pirates since signing a Minor League contract with the Bucs on Aug. 16 and being called up from Triple-A on Sept. 1. Closer Mark Melancon closed it out to pick up his 16th save.