Bregman was diagnosed with a strained right hamstring after leaving Wednesday's win over the Rockies, Chandler Rome of the Houston Chronicle reports.
Bregman sustained the injury running out a double during the fourth inning and was quickly removed after limping into second base. Manager Dusty Baker said he expects the 26-year-old to "be more sore in the morning than he is now," so he seems unlikely to be in the lineup for Thursday's series finale.