The presence of Quiroz, who accounted for the Giants' offense in the preseason finale with a three-run homer, will enable the Giants to use Sanchez as a pinch-hitter.
"He has a good, adjustable bat from both sides of the plate," Giants vice president and assistant general manager Bobby Evans said of Sanchez.
Sanchez's sore right shoulder appears to be less of an issue. He caught in a Minor League game Saturday in Arizona for the second straight day and, Evans said, "looks pretty good."
Quiroz, 31, has looked good through much of the spring, hitting .282 with 13 RBIs. He has compiled a .206 batting average in 103 games spanning eight seasons (2004-10, 2012) with Toronto, Seattle, Texas, Baltimore and Boston.
"He's gotten better with more playing time," Giants manager Bruce Bochy said. "His at-bats have gotten better, his catching, it looks like he's gotten in a good rhythm. He's got his confidence going and I like the way he's using the whole field at the plate. He's got some big hits, but you look more at the quality of the at-bats and they've gotten a lot better."
Dropping Gillespie meant that the Giants will begin the season with four outfielders, one fewer than the usual complement. But Evans pointed out that both Gregor Blanco and Andres Torres can play all three outfield spots, giving the Giants depth in skill if not in numbers. And first baseman Brandon Belt can substitute in left field if necessary.
Chris Haft is a reporter for MLB.com. Alex Espinoza is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.