Austin has replaced receiver Patrick Crayton, who had started the previous five games.
After Austin's franchise-record performance of 250 yards receiving on 10 catches during the game at Kansas City on Oct. 11, the team decided it was time for him to move into the starting lineup.
"Patrick has no comment, he just wants to go out and do his job," Crayton's agent Fred Lyles said late Monday.
Williams missed the Kansas City game with three bruised ribs but said he expects to play Sunday against Atlanta. If Williams is unable to play because of a setback in his rehab this week, Crayton would return to the starting lineup.
However, it's Austin's job as of now.
In Austin's first career start, he scored two touchdowns, including a 60-yard catch-and-run to win the game in overtime. Austin's performance earned him NFC Offensive Player of the Week honors, and his yardage total was the most in the league this season by a wide receiver.
"He had a great game, but now we've got to forget about that one and get ready for this one, and this is a big game for us coming up," receivers coach Ray Sherman said before Monday's practice. "That game is in the past as far as we're concerned. It's good to see him have success and now, he's got to be able to keep that up."
The Cowboys had high expectations for Austin at the start of training camp, but he couldn't unseat Crayton for the starting job and fell behind Sam Hurd on the depth chart.
When the regular season started, Austin was able to show the team his big-play ability when he caught one pass for a 42-yard touchdown, breaking a tackle in the process, in the season-opener.
But Austin had just four catches the next three weeks before the Chiefs game. He moved into the starting lineup when Williams was hurt. He scored both of his touchdowns while breaking tackles.
He also dropped two balls in the end zone, but the team remains confident in his abilities.
Calvin Watkins covers the Dallas cowboys for ESPNDallas.com. E-mail him at firstname.lastname@example.org.