The Cowboys officially placed rookie running back Phil Mafah and cornerback Caelen Carson on injured reserve/designated to return, the team announced Wednesday.
Mafah (shoulder) and Carson (knee) are required to miss at least four games before they can return.
The Cowboys replaced their roster spots by re-signing special teams ace C.J. Goodwin and offensive tackle Hakeem Adeniji to the 53-player roster.
Dallas released Goodwin and Adeniji in procedural moves Tuesday, with a plan to re-sign them Wednesday.
Goodwin is entering his eighth season with the Cowboys, having played 62 defensive snaps and 1,823 on special teams in his time in Dallas. He has 50 total tackles.
Adeniji is in his first season in Dallas, having played 43 games with 15 starts for the Bengals and Vikings.