The possibility of Tyron Smith missing a second straight game with a bone spur issue in his ankle has increased with every missed practice of the week.
"Terence Steele will take all the reps at left tackle again today," McCarthy said before Friday's walkthrough.
Steele started for Smith at left tackle against the Broncos and admitted after the game that playing the position was more challenging than he expected after having started at right tackle for La'el Collins earlier in the season.
McCarthy was clear that the window for Smith to be able to play against the Atlanta Falcons is closing rapidly.
"If Tyron doesn't practice [Saturday] he won't be available on Sunday," McCarthy said. "That's kind of the timeline that we're on."
Leading up to last week's game against the Broncos, McCarthy said that he did not believe Smith's injury to be a long-term concern. In Smith's absence, the Cowboys struggled on offense for the first three quarters of their loss to Denver.