Davis, the sixth overall pick in the draft, got hurt while trying to chase down Patterson from behind. Davis was taken off the field on a cart and is expected to miss four weeks.

“I was trying to tackle him and I just pulled up,” Davis said. “I didn’t make any contact. I felt something and just fell down.”

Davis said he bruised his calf in practice during the week and believed that might have contributed to the injury. Davis had no catches in San Francisco’s 38-24 loss to the Eagles and has five receptions for 37 yards and a touchdown this season.

Davis acknowledges it is frustrating to have a setback this early in his rookie season.