"Erik's going to have to show us something before the game," McCarthy said. "Obviously we're going over early, two o'clock, so we'll have a decision right there at the deadline."
Zombo is a rookie who stepped in as a starter in the middle of the season, but he missed the Packers' previous six games with a knee injury. Walden was signed in midseason and has played well.
"I really liked today's schedule because finally this gets you back on the routine you've been on for the last five years," McCarthy said. "We've had an opportunity for our final corrections in our meetings. The coordinators have given their last message to each unit, and they had their final walkthrough, like we always do. They're done for today, and we'll have a team meeting tonight."
Instead of switching hotels the night before the game as some teams do, the Packers were expected to spend Saturday night at the same hotel they have stayed at since arriving Monday.
"I've received feedback from clubs that have left the hotel and stayed," McCarthy said. "Seeking routine and consistency in how we've operated in the past, I chose to stay in the same hotel. I've heard positives from both sides."
The players were scheduled to be off the rest of the day Saturday until an 8:30 p.m. chapel service and 9 p.m. team meeting. McCarthy will hold his final team meeting at 10:30 a.m. Sunday before the team heads to Cowboys Stadium.
"To me, the preparation stress has just left the building," McCarthy said. "I think it's very important to put the players in a mental state where their mind is clear and it's time for them to prepare themselves for the game."
The Associated Press contributed to this report.