According to his agent, Rodney Edwards, Boyd broke his right ankle, and additional tests showed possible ligament damage. Edwards said Monday that he was awaiting word from doctors to determine the severity of the ligament damage. On Monday afternoon the Packers placed Boyd on season-ending injured reserve.
Boyd was injured in the second quarter and had to be carted off the field.
Edwards said Boyd may need surgery, which could require an eight to 10 week recovery.
However, in a possibly related move, the Packers signed inside linebacker Joe Thomas off the Dallas Cowboys' practice squad to their 53-man roster. Thomas was released by the Packers at the end of the preseason. He had spent part of last year on their practice squad.
The Packers were short an inside linebacker after Sam Barrington was placed on injured reserve last Tuesday because of a foot injury. Defensive end Datone Jones, who was suspended Week 1, took Barrington's spot on the roster.
Boyd, a fifth-round pick in 2013, has played in 26 career regular-season games.
The Packers also are dealing with ankle injuries to both running back Eddie Lacy and receiver Davante Adams. A source told ESPN's Adam Schefter that X-rays on Lacy's ankle were negative, but it's not known if Lacy will be able to play next Monday night against the Kansas City Chiefs. Adams returned to Sunday's game after missing part of the second quarter.