Preseason action kicks-off at 8pm eastern time, and you can watch streaming online here.
Last week, Dallas suffered a 28-20 loss to the San Diego Chargers on the road. Quarterback Tony Romo played only two series and went 9-for-13 for 75 yards, but did not have his top receivers for the second straight week.
Dallas' receiving corps has wilted due to injuries to tight end Jason Witten and wide receivers Miles Austin and Dez Bryant. All three will not play against St. Louis.
Kevin Ogletree and Dwayne Harris will start instead at wide receiver Saturday. Harris, along with Andre Holmes and Cole Beasley, are battling to make the squad.
Beasley was impressive against the Chargers, making seven receptions for 104 yards.
The Cowboys offensive line may be the healthiest it has been all season. Guard Nate Livings will make his first preseason appearance alongside guard Mackenzy Bernadeau and center David Arkin, who is filling in for starting center Phil Costa.
Romo's reserve receivers and his line will need to put up big points Saturday, as St. Louis quarterback Sam Bradford appears to be back in top form.
Bradford was 6-of-9 for 102 yards and two touchdowns in the first quarter of St. Louis' 31-17 rout of the Kansas City Chiefs. Former practice squad Cowboy Danny Amendola grabbed three receptions for 58 yards and a touchdown to lead the Rams' receivers.
Dallas could have its hands full with the St. Louis defense as well. The Rams forced four turnovers and recorded five sacks against the Chiefs.
Despite the team's overall success, new Rams head coach Jeff Fisher said most of the starters will only play the first half. He is waiting until the squad's final preseason game against Baltimore to play his starters into the second half.
Prediction: If Bradford is healthy the Rams can field a potent offense and take advantage of the injury-laden Cowboys. Dallas will need its second string receivers to step up against the Rams' emerging pass rush.
Predicted Score: St. Louis 24, Dallas 18