"I am happy to be able to go deep into the game and give those guys some rest," Perez (7-6) after holding the Phillies to one run on five hits.
"Tonight was special. I had confidence in all of my pitches, I got ahead and came out with the win," said Perez, who had a season-high eight strikeouts to help the Dodgers avoid a sweep in the three-game series.
He walked three.
Lieberthal's RBI single in the second inning provided the Phillies' only run.
Rookie Dioner Navarro had three hits, all singles, and drove in a run in the Dodgers' three-run fifth inning.
"Day by day, I'm feeling more comfortable," Navarro said.
Perez kept the Phillies guessing.
"He was throwing a lot of off-speed stuff," said Philadelphia rookie Ryan Howard, who struck out all three times up after homering in each of the previous two games. "He had his changeup and everything kind of sinking, and he mixed up his pitches.
"This was the first time I've faced him, and it's not the kind of night you want to have. But it's all a learning process. Now I've seen what he has, and you just kind of put it away for the future."
Philadelphia starter Cory Lidle (9-10) had control problems, giving up four runs on five hits and six walks in five innings. He threw 107 pitches and the six walks were double his high in 24 previous starts this year.
"I didn't feel out of whack out there. It was an unexplainable night," Lidle said. "I'll just forget about this one. The ball just wasn't going where I wanted it to.
"It seems like they (the Dodgers) were more patient, but the umpire was also pretty tight back there. I thought he missed a couple. And as a hitter, when the umpire's tight, you can afford to be more patient."
Lidle, who had given up only three walks total in his previous seven starts, walked Oscar Robles and Jayson Werth in succession leading off the Dodgers' fifth inning. Milton Bradley hit a low drive that bounced off third baseman David Bell for an infield single and loaded the bases. Kent followed with a drive down the left-field line to give Los Angeles a 3-1 lead. The two RBI gave him a team-high 80.
After the Dodgers got a run in the first, the Phillies evened it in the second when Chase Utley led off with a triple and scored on Lieberthal's hit.
Jose Valentin's RBI single in the opening inning had given the Dodgers their short-lived lead.
- Dodgers RHP Yhency Brazoban, who has converted 21 of 25 save opportunities in place of the injured Eric Gagne, is out of the closer role after giving up a tiebreaking grand slam to Howard in the ninth inning of Wednesday's 9-5 loss. Tracy said before the game that he will use Duaner Sanchez and Steve Schmoll to close until Brazoban regains his form. Sanchez pitched a 1-2-3 ninth in Thursday's win.
- Los Angeles activated Werth from the disabled list earlier in the day and placed LHP Wilson Alvarez on the 15-day DL with a shoulder problem.
- The Phillies are 16-6 against NL West teams this year and have three-game series against San Diego, San Francisco and Arizona remaining this month, all on the road.
- Dodgers SS Cesar Izturis sat out because of soreness and stiffness in his lower back.