Dodgers starter Clayton Kershaw (1-1) walked his first two batters of the game, and both scored when Doumit's sinking liner got past Kemp in center with two outs as he tried to backhand it on the short hop.
Kemp, who won his first Gold Glove last season, was criticized earlier this week on the team's flagship radio station by general manager Ned Colletti about his fielding this year while the Dodgers were in New York.
Brian Burres (1-1) allowed four hits over 5 1-3 innings with four walks and three strikeouts. The Pirates have won three straight.
Burres escaped a bases-loaded jam in the fourth when he retired Jamey Carroll on a fielder's choice grounder, but was pulled after issuing a pair of one-out walks. Jack Tashner retired all eight batters he faced without allowing a ball out of the infield, and Evan Meek pitched a perfect ninth for his first major league save.
Kershaw allowed three hits over 6 1-3 innings, striking out seven and walking four. Manager Joe Torre tried to get his 22-year-old lefty through the seventh, but had to yank him after he walked Tashner with his 117th pitch. Kershaw has given up no more than two runs in any of his past four starts.
Pirates right fielder Garrett Jones allowed Blake DeWitt's one-out single in the third inning to scoot by him. DeWitt ended up on third — but unlike Kemp, Jones was charged with a two-base error by official scorer Don Hartack.
After a walk to Kershaw, Russell Martin hit a liner that struck DeWitt in foul territory and knocked him flat. He stayed in the game after being checked by trainer Stan Conte.
But the Dodgers came up empty, as Kershaw was thrown out at second trying to advance on a pitch in the dirt that bounced a few feet to the left of Doumit, and Martin grounded out.
Carroll again started at shortstop in place of Rafael Furcal, who missed his third straight game with a left hamstring strain. He was examined by team Dr. Neal ElAttrache on Thursday and received a platelet-rich plasma injection to promote healing.
NOTES: When Kemp got to his locker before the start of the 10-game homestand, he was surrounded by reporters asking him about Colletti's criticism. "I don't really want to talk about it anymore," Kemp said. "It's old news to me. It's squashed, so why would I talk about something that's already squashed? I want to beat these Pirates and get some Ws on the board. Wouldn't that be fun, huh?" ... Doumit's triple was his fourth in the majors and first since Aug. 11, 2007. ... Torre selected RHP Carlos Monasterios to make his first big league start Saturday. Monasterios, who has made seven relief appearances this season, started 60 games during his five seasons in the minors.