OXNARD, Calif. -- After missing last year recovering from a torn anterior knee ligament at the University of Texas, Chris Whaley’s career with the Dallas Cowboys is once again on hold.

Whaley suffered a torn Achilles in Monday’s workout and will undergo surgery, according to a source. Two years ago Tyrone Crawford suffered a similar injury on the first day of camp and missed the 2013 season.

While Crawford has been able to recover quite well, Whaley might not get the same benefit of the doubt with the Cowboys. He was a longshot to make the 53-man roster but had a chance to make the practice squad.

With Whaley out and Terrell McClain (bone bruise, hamstring) and Nick Hayden (ribs) missing time, the defensive tackle ranks are thinning out. In addition to Crawford, the Cowboys have only Ken Bishop and Davon Coleman as true defensive tackles. Jack Crawford has spent camp playing defensive tackle but is more of a defensive end. Ben Gardner can also spend time in the base defense at defensive tackle.