According to the Associated Press, Lance Berkman will have minor surgery on his left knee Saturday and will miss two to four weeks. It’s possible that the All Star first baseman will Opening Day.

Berkman, 34, injured his knee during a base running drill early last week, but played five Spring Training games. The diagnosis is a bruised knee. The swelling in the knee prompted doctors to operate on the injury. The first baseman had arthroscopic surgery on the same knee in 1999.

Berkman is entering the final season of an $85 million, six year contract extension. He hit .274 with 25 home runs and 80 RBIs with the Astros in 2009. You can see Berkman’s contract history and statistics here.