The Dodgers activated outfielder Manny Ramirez for Thursday night's game against the Cardinals and replaced him on the 15-day disabled list with outfielder Reed Johnson, with chronic lower back issues. The 33-year-old Johnson has a history of back problems, having missed three months in 2007 with a herniated disk and spent stints on the disabled list in '08 and '09 with back spasms. Ramirez was disabled with a strained right hamstring suffered running the bases in San Francisco.