Specifics regarding the knee injury weren't immediately made available, but Rapoport cited a source who said it's "not thought to be major."
Adam Jahns of the Chicago Sun-Times added Sanchez is expected to be healthy in time for the start of training camp.
The Bears previously announced they had waived quarterback Connor Shaw to clear a roster spot for wide receiver Victor Cruz, but Rapoport reported the team rescinded the waiver request following Sanchez's injury.
Chicago now has three healthy quarterbacks at its disposal for OTAs in starter Mike Glennon, Shaw and 2017 first-round pick Mitchell Trubisky.
Sanchez, 30, signed a one-year, $2 million deal with the Bears in late March that includes $1 million guaranteed.