The Patriots announced they placed linebacker Brandon Copeland on injured reserve Wednesday.
Copeland told teammates he tore a pectoral muscle Sunday against the 49ers.
He appeared in six games, starting four, in his first season with the Patriots after signing as a free agent in March. He has 10 tackles on defense and two more on special teams.
Copeland, who entered the league as an undrafted free agent in 2013, has played for the Lions and Jets.
In 2017 with the Lions, Copeland tore a pectoral muscle in the preseason, landing on IR.