The veteran left-hander continued his torrid start, scattering two hits over seven innings and the Pirates edged the Chicago Cubs 1-0 on Wednesday night.
Liriano (3-0) struck out nine and walked just one to remain unbeaten since making his season debut against the New York Mets two weeks ago.
"What was it, one walk, nine punchouts and two hits?" Pittsburgh manager Clint Hurdle said. "Man, that's clean stuff."
You won't find the Cubs arguing after Liriano escaped a bases-loaded, no-out jam in the third inning unscathed and then cruised. The Cubs went 0-for-6 with runners in scoring position and are hitting just .160 (4-for-25) with runners on base during their three-game losing streak.
"It's the same old song and dance," Chicago manager Dale Sveum said. "We get people on but can't get them in."
Mark Melancon survived a bumpy ninth inning for his first save of the season. The Pirates were forced to sit closer Jason Grilli -- whose 18 saves lead the majors -- after he labored through 34 pitches in a 5-4 win on Tuesday.
The road to Melancon's first save since Aug. 26, 2012, while pitching for Boston wasn't exactly smooth.
The Cubs put runners on first and second with one out but couldn't tie things up. Melancon, who has served as the primary setup man this season, didn't feel any extra jitters getting the last three outs.
"I do it every night, it's just in the eighth inning instead of the ninth," Melancon said.
Andrew McCutchen doubled twice for the Pirates and scored the game's only run on an RBI single by Garrett Jones in the first. Pittsburgh has won 10 of 12 to move 10 games above .500 (28-18). The Pirates have also won six straight one-run games.
"I love the way we're going about our business," Hurdle said.
Chicago's Jeff Samardzija (2-6) nearly matched Liriano pitch for pitch, giving up just three hits in seven innings, but received little help once again.
The Cubs have scored just 10 runs in Samardzija's losses. The right-hander's only issue came in the first when McCutchen doubled with two outs then scored on a single by Jones.
It would be all the cushion the Pirates needed while Samardzija lost a 1-0 decision for the second time in a month.
"You take it with a grain of salt," said Samardzija, who walked one and struck out eight. "That's just the way the game goes sometimes. You give up five runs and get a win sometimes."
Or, in the case of the Pirates, whenever Liriano is on the mound.
The Pirates agreed to terms with the former All-Star in December, but Liriano signed a more incentive-laden deal after breaking his right (non-throwing) arm in a freak accident on Christmas Day.
It's certainly looking like a bargain now. The left-hander has spent most of the five seasons attempting to regain the form he showed as a 22-year-old phenom with the Minnesota Twins in 2006, when he went 12-3 with a 2.16 ERA and made the All-Star team on his way to finishing third in American League Rookie of the Year voting.
His path to stardom was sidetracked by Tommy John surgery in 2007, though he appears to have found a home in Pittsburgh.
"I think I work hard in the offseason, location-wise with my fastball and everything is working so far," Liriano said. "Pitching is all about location so when you can locate your pitches, you have better results."
He was solid in his first two starts in wins over the Mets and Milwaukee. He was spectacular at times against the Cubs. He retired 14 of 15 batters at one point and managed to expertly wiggle out of the lone spot of trouble in the third when the Cubs loaded the bases with no outs following a Cody Ransom single, a walk and an error.
In a way, Liriano had the Cubs right where he wanted them.
Chicago began the night hitting just .218 with runners in scoring position, the second-lowest in the majors.
No Cub made it to third base over Liriano's final four innings and Pittsburgh's bullpen made it hold up. The Pirates are 21-1 when leading after seven innings this season.
Tony Watson worked the eighth and the Cubs made Melancon work in the ninth.
Alfonso Soriano reached on strikeout-wild pitch and Wellington Castillo singled with one out. Nate Schierholtz and Darwin Barney both lofted weak fly balls to shallow right field that Pittsburgh second baseman Neil Walker corralled with ease.
Chicago's Darwin Barney, who went 4 for 4 in the series opener on Tuesday to raise his average from .192 to .223, went 0 for 3 ... Pittsburgh's left-handed starters are 8-1 at PNC Park this season ... The series wraps up on Thursday. Jeanmar Gomez (2-0, 2.78 ERA) will make his first start against the Cubs. Edwin Jackson (1-6 5.76) starts for Chicago. Jackson is 4-1 with a 3.09 ERA against the Pirates in his career.