Los Angeles Dodgers outfielder Matt Kemp, who enjoyed a sensational start to 2012, was back on the disabled list Thursday, two days after returning to action. Kemp aggravated a left hamstring strain during Wednesday\'s loss to Milwaukee. ESPN quoted Los Angeles trainer Sue Falsone as saying Kemp would be out a minimum of four weeks. Kemp first went on the DL with the hamstring problem May 14. His latest troubles came in only his second game back. During the month of April Kemp hit 12 home runs and had 25 RBI while batting .417. He was the early National League leader in all three categories. Kemp played in only 13 games during May, however. He did not hit a home run during the month, had just nine RBI and his batting average dipped to .355. Infielder Alex Castellanos was called up to take Kemp\'s place on the roster. The Dodgers conclude a four-game series with Milwaukee Thursday, having lost the first three games for their first three-game losing streak of the season.