Jody Gerut, who has been platooning with Scott Hairston in center field, moved from the leadoff spot to No. 3 in the lineup for the first of four games against the Dodgers starting Thursday.
"Brian has led off before," Black said. "It's to get Brian a different perspective in the lineup ... and for Jody, too."
Giles entered Thursday's game hitting .169 while almost hitting exclusively third in the lineup. Gerut, coming off a three-hit game in Colorado on Monday, entered the game on Thursday hitting .246.
Giles is no stranger to hitting leadoff. Although it's the first time he's done so this season, he has 598 career at-bats at the top of the order with a .283 batting average and .376 on-base percentage compared to his overall career numbers of .293 (average) and .402. (on-base).
Last season, Giles hit .308 in 49 games in the leadoff spot. He hit .269 in 78 games while in the leadoff spot in 2007.
"We'll see what that does with our ability to score runs," Black said of the move.
The Padres, who started the season with a 9-3 record, have scored three or fewer runs in four of their past nine games. Scoring runs doesn't figure to be easy this weekend against a Dodgers rotation that includes Clayton Kershaw, Randy Wolf and Chad Billingsley.
The Padres split a four-game series to open the season in San Diego earlier this month.
"It's sometimes subtlety moving a guy. This is something that happens with other clubs," Black said of making changes in the lineup.
Earlier this season, Black moved Kevin Kouzmanoff from fifth in the order to sixth in the lineup, a move that helped him and Chase Headley.
Headley is tied for second on the Padres in RBIs (11) and has provided some protection in the lineup for Adrian Gonzalez, who has hit a franchise record nine home runs this month while Kouzmanoff has hit in nine of his past 12 games and is hitting .300 in that stretch.
Corey Brock is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.