Geovany Soto also drove in two runs for Chicago, which improved to 40-15 at Wrigley Field after losing 3-0 to the Pirates on Friday. The Cubs (66-45) have won six of seven to improve to a season-best 21 games over .500 for the second time this season.
Lilly (11-6) allowed one run and five hits, improving to 10-2 in his last 12 decisions.
"I'll tell you what, over the past two years after losing a ballgame, this guy does just as good as a job as any, anybody we have here putting a stop to that losing streak," Piniella said. "You look at his performance, he's a gutsy kid. He doesn't back off and he gets after it and it shows. Even though early in the game at times he wavers a little bit, boy, he collects himself and digs in and does a heck of a job."
After throwing 54 pitches in the first two innings and battling early control problems, Lilly finished strong and left to a loud ovation in the seventh inning. The left-hander praised rookie catcher Soto for helping him settle down.
"He kind of knew I was scuffling with my curveball and he kind of helped me have a little more confidence and made me throw my changeup a little bit more and use my slider," Lilly said. "Sometimes I get stubborn out there and when something is not working I'll force it to work and he was good with me in that regard."
"We couldn't get much going," manager John Russell said. "We had some chances against Lilly early but couldn't get the big hit."
Maholm drove in Doumit with an infield hit in the second but the Cubs pushed across two runs in the bottom half. Aramis Ramirez reached on a leadoff double, advanced to third on Johnson's single and scored on Soto's groundout. Ronny Cedeno singled in Johnson to make it 2-1.
"I had Lilly on deck, I knew it, didn't want to throw him a strike anywhere close to the zone and I threw it right down the middle," Maholm said about Cedeno's hit. "That pretty much sums up how my location went all day."
Soto singled in Johnson in the fourth and Mark DeRosa scored when Cedeno grounded into a double play. Alfonso Soriano led off the fifth with a double down the left-field line and scored on Derrek Lee's sacrifice fly to make it 5-1.
Chicago is getting good production from the center-field platoon of Johnson and Jim Edmonds, who hit a grand slam and solo shot in Thursday's win against the Brewers.
"They are both good on the defensive end as well, and they bring a lot to our table," Lilly said. "It's kind of interesting they bring different facets of the game. Jimmy is dangerous with one swing of the bat and Reed kind of brings a different factor in the game when he's in the lineup."
Maholm gave up five runs and eight hits in six innings.
Cubs RF Kosuke Fukudome didn't start, but had a pinch-hit single in the seventh inning and stayed in the game in right. ... The Cubs have won their last five games against left-handed starters. ... Lilly had his 10th quality start in his last 12 outings. ... Maholm gave up more than three runs for the second time in his last nine starts.