By Simon Evans
Walden was listed as "questionable" on the official injury report after spraining an ankle in last month's NFC Championship win over Chicago.
Frank Zombo is almost certain to start if Walden doesn't recover in time for the clash at Cowboys Stadium.
Wide-receiver Donald Driver was left out of the main team drills on Friday due to a quadriceps strain but McCarthy said he was expected to play and described the move as merely a precaution.
"We've had an opportunity to go over every situation twice for our game plan, so we're ready to go," he said as the team left their Highland Park High School indoor practice facility.
"We respect Pittsburgh but we feel that this is our time and Sunday will be our night."
(Editing by Julian Linden)