The Brewers’ situation at first base changed Friday when they learned Corey Hart will need knee surgery that will make him miss at least the first six weeks of the 2013 season.

Hart, who had surgery on his right knee last spring to repair cartilage damage, experienced swelling in that same knee during offseason workouts and was examined in Phoenix by team physician William Raasch. An MRI was performed that revealed a defect in the joint surface.

Raasch will perform surgery Tuesday in ...