Rough news for the Giants: Third baseman Pablo Sandoval has fractured the hamate bone in his left wrist, the team announced Thursday. He will undergo surgery Friday, Giants manager Bruce Bochy told the Giants beat writers. Sandoval is expected to miss four to six weeks.

Andrew Baggerly of CSN Bay Area reports that Sandoval had been trying to play through the pain the "last couple days" but the "pain became unbearable [Wednesday night]."

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Sandoval left the game Wednesday night after grounding out in the sixth inning. He has had wrist issues before, as surgery on his right wrist cost him 41 games last season.

Sandoval, 25, is hitting .316/.375/.537 with five homers, 15 RBI and 16 runs this season. He's a career .308 hitter with an .859 OPS and, along with Buster Posey, Sandoval is one of the anchors of the Giants' offense. So, yes, it's an understatement to say this injury is a huge blow to San Francisco.

The Giants' replacement options at third base in the short term look to be a combination of Joaquin Arias and Conor Gillaspie. Arias is hitting .375/.412/.563 in just 17 plate appearances. He's a career .282/.319/.374 hitter in 292 plate appearances spread across five different seasons with three teams.

Gillaspie, 24, hit .263/.333/.421 in 21 plate appearances for the Giants last season. He's hitting .362/.417/.521 with six doubles and three homers in 23 Triple-A games this season. Gillaspie is in the Giants' lineup Thursday at third base.

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