PHOENIX -- Oakland Athletics closer Grant Balfour is scheduled for arthroscopic surgery on his right knee Thursday afternoon.

The A's made the announcement that the right-hander is expected to miss four to six weeks, and decided to have the procedure now with the hopes of returning for the start of the season.

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The 35-year-old Balfour went 3-2 with a 2.53 ERA and 24 saves last season for the AL West champions.

The A's exercised their $4.5 million contract option for the Australian reliever shortly after the team lost in a five-game division series to the Tigers.

He made 75 appearances spanning 74 2-3 innings in 2012, his ninth year in the majors. Balfour began the season as the closer, lost the job, then earned it back again down the stretch.