Twins activate IF Lewis from injured list after month-long absence

Lewis missed 36 games with left oblique strain.
Lewis went 4-for-7 with two home runs in rehab assignment before activation.
Lewis was hitting .326 with four home runs and 15 RBIs before injury.
Twins placed UT Willi Castro on injured list with left oblique strain to make room.
Twins hold 41⁄2 game lead in AL Central entering game vs. Tigers.