IRVING, Texas -- With Anthony Spencer's availability for Sunday's season opener against the New York Giants in doubt because of knee surgery, the Cowboys added a second defensive end to the roster in four days by trading for Caesar Rayford.

The Cowboys sent a conditional 2015 draft pick to the Indianapolis Colts for Rayford, who had five sacks and 11 tackles in the preseason. Dallas traded with the Kansas City Chiefs for Edgar Jones on Saturday, although Jones is viewed more as a special teams player.

Spencer had surgery on July 25. He has said continuously he would be ready to play against the Giants, but he has yet to practice and was not on the field Monday for the portion of the session open to the media.

On Monday, coach Jason Garrett said he hoped Spencer would be able to work back into practice as the week goes on, but he also acknowledged conditioning would be a factor for Spencer.

"We've just got to see how he does, how he responds to the work," Garrett said. "He's been working hard to get back. We appreciate that. I know how much desire he has to play. He's a real pro and he's doing everything he can to get healthy and be ready to do. So we will see how he does over the next couple of days and make a decision."

Rayford spent three seasons with the Arena Football League's Utah Blaze and recorded 22.5 sacks. He played for the B.C. Lions of the CFL from 2008-09 after his career at the University of Washington.