Manager Bruce Bochy said Sanchez will have a microdiscectomy performed by Dr. Robert Watkins on Wednesday to remove part of a disc, the latest and perhaps most serious setback in the second baseman's injury-marred tenure with the Giants.
"You know he's disappointed," Bochy said. "He played a critical role in our success in 2010."
The 34-year-old three-time All-Star and 2006 NL batting champion became the first player in major league history with three doubles in his first three World Series at-bats two years ago when the Giants captured their first championship since moving West to San Francisco. Sanchez also kept his team alive with a ninth-inning single in a memorable Game 3 victory over the Atlanta Braves that year in the playoffs.
"That base hit, I'll always remember it," Bochy said. "It would be a lot tougher if we had lost that game. Obviously one of the bigger hits in the postseason."
But Sanchez has spent the bulk of the time just trying to stay healthy since joining the Giants in a trade-deadline deal with the Pittsburgh Pirates in 2009. He had surgery on his left shoulder in December 2009 and December 2010 and on his right shoulder in August 2011. His back started acting up during rehab work this year, and he had an epidural in his lower back in May.
Sanchez will make $6 million this year and is scheduled to become a free agent at the end of the season.
"You don't know what's going to happen when the season's over," Bochy said.