Freddy Sanchez's 2012 season is over before it even starts. He underwent back surgery Thursday, Hank Schulman of the San Francisco Chronicle reported.

Sanchez signed a $6 million extension covering the 2012 season on April 1st, 2011. Given the large uphill battle he faces with rehab from the surgery, his career with the Giants -- and potentially all of baseball -- could be over. 

Sanchez hit .290/.333/.387 in two-plus years as a Giant.