"This is a big opportunity for him," McCarthy said. "He's had a good week's work, and I'm sure he's up to the challenge. I like what I've seen."
Jones will start in place of Aaron Kampman, who will miss his first game because of injury since October 2003. Kampman is recovering from a concussion he sustained during the Packers' loss at Tampa Bay last Sunday.
"As much as it hurts (to not play) -- I want to be there for this one -- this is probably the right thing to do," said Kampman, who didn't practice this week.
Brady Poppinga, a potential fill-in for Kampman, also won't play Sunday because of a quadriceps injury.
That leaves Jones, a seventh-round draft pick, to fill the void at left outside linebacker against the Cowboys' high-powered offense. Jeremy Thompson, another young player with no starting experience at linebacker, also was under consideration at the position.
Green Bay's coaches believe Jones is ready to handle a prominent role after a back injury stunted his development during the preseason. Jones has been a major contributor on special teams, making eight tackles in the first half of the season.
Kampman said he would be on the sideline Sunday to provide in-game guidance to Jones.
Meanwhile, inside linebacker Brandon Chillar hasn't been ruled out from playing against the Cowboys. Chillar missed the last game because of a broken right hand, which required the insertion of nine pins and a plate in surgery last week.
Chillar was fitted with a big club-like cast and wore it for the first time as he practiced on a limited basis Friday.
"Playing football one-handed is definitely not fun," said Chillar, who's questionable for Sunday's game.
Copyright 2009 by the Associated Press