Greenlaw (core) is listed as day-to-day according to coach Kyle Shanahan, Cam Inman of The San Jose Mercury News reports.
Greenlaw left last Sunday's win over the Vikings early after suffering what appears to have been a core issue. The linebacker had just returned from a long hiatus due to a groin injury suffered in the season opener. The 49ers defense may be in desperate need of their Week 1 starter's services with fellow linebackers Fred Warner (hamstring) and Marcell Harris (concussion) potentially out this Sunday against the Seahawks.