Harang, in his first year with his hometown team after spending seven full seasons in Cincinnati, has already won more games (13) in 27 starts in 2011 than he won over his previous two seasons with the Reds (12) in 48 outings.
The 33-year-old was among the National League's best pitchers and won 16 games in consecutive seasons in 2006 and 2007, but tumbled to six wins apiece over the next three years and was not re-signed when his contract expired.
He got off to an instantly good start with the Padres, winning his initial four starts in April and getting to 9-1 with a 5-4 win in Philadelphia on July 25.
He's faced the Dodgers twice this season and been effective both times, getting a win and a no-decision while giving up just one earned run on three hits in 12 innings.
He threw six no-hit innings against Los Angeles on July 9, but was coming off an injury and was pulled after six when his pitch count reached 95. San Diego lost the game, 1-0.
Lilly (11-14) allowed four hits and fanned seven to move to 10-4 lifetime against the Padres.
Wade LeBlanc (4-6) surrendered four hits and had a career-high 10 strikeouts over seven innings, but the Padres couldn't build on their three-game sweep in Colorado.
"I don't think his velocity wavered through seven innings," Padres manager Bud Black said.
Jerry Sands doubled leading off the second and scored on a Russ Mitchell groundout.
San Diego left a runner in scoring position in the third and fourth frames, and Kemp went deep to right leading off the seventh. Kemp's homer was his 37th, tying him with St. Louis' Albert Pujols for the National League lead.
"I just have to relax, not try to hit home runs and try too hard," said Kemp, who is trying to become the first Triple Crown winner since Boston's Carl Yastrzemski in 1967. "I just relax and have fun. What ever happens is going to happen."
The Dodgers start righty Chad Billingsley, who can reach 12 victories for the third straight season.
The 27-year-old Ohio native, who was 12-11 in 2009 and 12-11 again in 2010, improved to 11-10 this season when he beat Pittsburgh, 15-1, in his last start on Sept. 18.
He has not lost since Aug. 21 in Colorado.
He last faced the Padres on July 8 in Los Angeles and emerged with a 1-0 win after giving up just four hits and striking out five in eight innings.
Billingsley is 11-7 against them in 24 career appearances with a 2.76 ERA across 127 1/3 innings.
Los Angeles has owned the Padres this season, going 12-4 against them, including wins in five of the seven meetings in San Diego.