Benjamin injured himself when he bumped knees with a defensive back in practice Sunday.
Rivera said the knee is stable and has swelling, and that there there is no timetable for Benjamin’s return, but said it was a matter of days, not a longer period.
The Panthers selected Benjamin with their first-round pick in the 2014 NFL draft.
The Panthers made several changes at the wide receiver position this offseason. The team released veteran Steve Smith and let Ted Ginn Jr., Brandon LaFell and Domenik Hixon leave via free agency. The quartet accounted for 156 receptions and 1,983 receiving yards in 2013. Carolina also signed Jerricho Cotchery, Jason Avant and Tiquan Underwood.
The 23-year-old Benjamin had 54 catches for 1,011 yards and 15 touchdowns at Florida State last year.
- Ben Estes