Ramirez felt tightness in his right side before Friday night's game, the start of a three-game series with Milwaukee. He walked in the first inning before being removed in the bottom half.
Ramirez is hitting .277 with 12 homers and 58 RBIs in 100 games for the NL West leaders. He had an MRI on Saturday, and manager Don Mattingly said the severity of the injury was not as bad as initially feared.
The move was made retroactive to Saturday, and Mattingly indicated Ramirez may just need the minimum 15 days to recover.
''We're probably being a little cautious,'' he said. ''He could be ready in 10 games but we don't want to (bring) him back in seven and then have something worse happen and maybe lose him the rest of the year. We want to assure ourselves he'll be available down the stretch.''
Infielder Darwin Barney, who was acquired in a July 28 trade with the Chicago Cubs, was called up from Triple-A Albuquerque to take Ramirez's roster spot. Miguel Rojas started at shortstop on Sunday with Los Angeles trying to avoid a three-game sweep against the NL Central leaders.
Mattingly said he planned to ''mix and match'' at shortstop in the interim, with Barney in the mix.
It was the latest move this week for the busy Dodgers, who had a National League-best 66 wins entering Sunday. On Saturday night, they acquired right-hander Kevin Correia from the Minnesota Twins for a player to be named later or cash.
Los Angeles is in the midst of a 20-day stretch without a day off, and Mattingly said Correia likely would make a spot start Monday in Atlanta. The rest of the rotation would be bumped a day for extra rest.
Since Aug. 1, the Dodgers have placed pitchers Paul Maholm, Chris Perez, Paco Rodriguez and Josh Beckett on the disabled list. They acquired Roberto Hernandez from Philadelphia last week to take Beckett's spot in the rotation.
''As of right now, we'll use (Correia) for a spot start and out of the bullpen,'' Mattingly said. ''Hypothetically speaking, during this stretch of games in a row we can give our guys a bit of a breather.''