Klesko broke out of a slump with three hits and two RBI, and the Padres ended Los Angeles' eight-game winning streak with a 6-1 victory Thursday night.
The Dodgers had matched the 1940 and '55 teams for the best start in franchise history with a 12-2 mark through 14 games. The '55 World Series championship club is the only Dodgers team to start 13-2. The Brooklyn Dodgers began that year 22-2.
Adam Eaton (2-1) pitched into the sixth inning and allowed a run on five hits with two walks and two strikeouts as the Padres ended a four-game losing skid to the Dodgers.
"It's nice to break that little streak we had going against us," Padres manager Bruce Bochy said. "Adam did a good job, he worked hard out there. It probably wasn't his most efficient outing, but he got it done."
Klesko, who went 3-for-3 to raise his average from .202 to .264, has reached base in six of his last seven plate appearance.
"We didn't want to face them again in June or July and not have a win against them," said Phil Nevin, whose sacrifice fly gave the Padres a 1-0 lead in the first inning before Klesko had a two-out RBI single off Dodgers starter Scott Erickson.
Erickson (1-1), who beat the Padres last week in Los Angeles, lasted just 4 2/3 innings. He gave up five runs and nine hits, and walked two and struck out four.
"Giving up three runs with two outs in the fifth inning turned out to be a little more than we could overcome today," Erickson said. "I was trying to keep the fastball down and change speeds a little bit, and make them get three or four hits to get a run and that's what they did."
Ramon Hernandez, who went 3-for-4, chased Erickson with a two-run single to right.
San Diego used its speed on the basepaths to help generate a pair of runs in the first inning.
Dave Roberts led off with a single and stole second. Loretta then hit a drive off the leg of Erickson for an infield single advancing Roberts.
After Erickson struck out Brian Giles, Nevin hit a sacrifice fly to deep center. Loretta moved up to second on the play. Klesko then hit an RBI single to center.
The Padres scored a run in their half of the sixth on an RBI double by Roberts.
Cesar Itzuris and Hee-Sop Choi had two hits each for the Dodgers.
Dodgers manager Jim Tracy and Valentin were ejected in the ninth inning by home plate umpire Andy Fletcher for arguing a called third strike.
- The Padres honored Ken Caminiti, who died last fall of a cocaine and opiates-induced heart attack at the age of 41, with a pregame ceremony. His wife and three daughters were presented with posters and autographed baseballs from Padres manager Bruce Bochy, Mark Sweeney and Trevor Hoffman. A video biography of Caminiti was shown on the Jumbotron. Caminiti's No. 21 was stenciled on the grass behind home plate. Caminiti played for the Padres from 1995 through 1998. He was the National League MVP in 1996 and helped the Padres to the 1998 World Series.
- Dodgers catcher Jason Phillips extended his hitting streak to eight game with a single in the fourth inning. Phillips has struck out just twice in 50 plate appearances.
- Milton Bradley, who had at least one hit in each of his first 13 starts, was held hitless in four at-bats Thursday. The Dodgers center fielder also threw out runners at third and home.