Armstrong came to Valley Ranch last week for a workout and after seeing the Cowboys lose receiver Miles Austin to a hip injury on the Thanksgiving Day game, he got ready.
"I saw that and I started stretching," Armstrong said after Monday's light practice at Valley Ranch. "Actually, I was eating Thanksgiving dinner and I was like, 'Alright this might happen and I might be participating a lot sooner than some may expected.' I'm ready for the challenge. It's always exciting to go to a new team and learn new things. I'm looking forward to it."
Armstrong was signed to help out a receiving corps that is missing Kevin Ogletree (concussion) and Austin. Ogletree and Austin both said they were hopeful they could practice Wednesday.
The Cowboys will use Armstrong on offense and special teams. His 4.2 speed allows him not only to stretch the defense in the passing game, but he's somebody who can get downfield and make a few tackles on special teams. It's that speed which attracted the Cowboys when they first saw Armstrong in 2007 when during a workout he ran a 40-yard dash in 4.24 seconds. Armstrong played with the Dallas Desperados, an Arena League team owned by the Jones family.
Armstrong played two seasons for the Washington Redskins, where he caught 51 passes and five touchdowns. In 2012 he played five games in Miami and after his release was picked up by Jacksonville before being cut.
"I feel like I can play 20-30 plays if I can," he said. "Being in the league a little bit you kinda know what it takes to participate to compete and play special teams right away. As long as the coaches and Tony (Romo) feel comfortable with me in the offense, I will try to make an impact right away."