Kosier, Colombo held out of Wednesday's practice
Colombo was expected to miss 2-to-4 weeks after having arthroscopic surgery to remove loose particles in his right knee in mid-August.
Kosier has a strained medial collateral ligament in his right knee. He is three weeks into a recovery that was slated to take 4-to-6 weeks.
Tackle Sam Young also missed practice for Dallas, which opens the season Sunday night against Washington.