Pence left Wednesday night's game at the Atlanta Bravesafter injuring his hamstring for the second time in two weeks.
He stopped about halfway down the first-base line after hitting a slow grounder to third base in the fourth inning and grabbed the back of his leg as he leaned over.
"Unfortunately [Pence] did a pretty good job on it," Giants manager Bruce Bochy told reporters Thursday morning. "That's a shame."
Pence was helped off the field, and Jarrett Parker took over in right field. Pence was hurt in the at-bat after Brandon Belt's two-run homer gave the Giants a 2-0 lead.
Outfielder Mac Williamson was recalled from Triple-A Sacramento to take Pence's roster spot.
Pence, who is tied for the team lead with seven homers and leads the Giants with 36 RBIs, returned to the lineup Saturday after not starting in six straight games with a right hamstring injury.
The Associated Press contributed to this report.
Pence leaves game with hamstring strain
Hunter Pence has to leave the Giants-Braves game with a strained right hamstring. This is Pence's second right hamstring injury in two weeks.