His status for Sunday's second preseason game is also uncertain.
With Austin out, Kevin Ogletree worked with Dez Bryant on the first team.
"Just got to see day to day and we don't think it's a serious injury," coach Jason Garrett said of Austin. "We didn't think it was smart to have him go out and practice [Thursday]. We'll see how he responds on treatment [Thursday afternoon] and make a judgment on tomorrow's practice."
Austin hurt the leg on a catch down the middle of the field during a two-minute drill Tuesday but stayed on through the rest of practice. He has received treatment the past two days.
Ogletree is in the lead for the No. 3 wide receiver spot, but has been inconsistent during camp.
Rookies Dwayne Harris and Raymond Radway could get more work to help their chance at earning a roster spot.
Austin's absence also highlights a potential issue should he or Bryant get hurt during the regular season. The receivers on the roster not named Austin or Bryant have 11 career catches, with 10 coming from Ogletree and one from Manny Johnson.
Calvin Watkins covers the Cowboys for ESPNDallas.com. ESPNDallas.com's Todd Archer contributed to this report.