The Cowboys are planning to place rookie running back Phil Mafah on injured reserve with a return designation, per ESPN’s Jeremy Fowler.

Mafah, a seventh-round pick, suffered a shoulder injury in the Cowboys’ final preseason game against the Falcons on Friday. He will be sidelined for at least the first four weeks of the regular season.

Dallas has carried three running backs (plus fullback Hunter Luepke) on their initial 53-man roster in each of the last two years. Two of those spots will be filled by Javonte Williams, Miles Sanders and Jaydon Blue. That left Mafah competing with 2023 sixth-rounder Deuce Vaughn and former UDFA Malik Davis to convince the team to roster a fourth running back.

Davis led the backfield statistically in the preseason with 70 rushing yards (50 of which came after contact), 7.8 yards per carry, and four runs of 10 yards or more, per Pro Football Focus (subscription required). However, the Cowboys’ distribution of playing time suggests that Vaughn and Mafah were still ahead (in that order). With Mafah sidelined, Vaughn would be in line for a fourth RB roster spot – if it exists.

However, Mafah’s return designation means that he could be back as early as Week 5. The Cowboys’ top three running backs should be able to get the team through the first four games, at which point Mafah could be added back to the active roster as the RB4. That would allow Dallas to open up another roster spot during final cuts this week and figure out a way to make room for Mafah during the regular season.