Phil Costa went down with a sprained knee, and the Cowboys turned to Kowalski, an undrafted free agent guard from Toledo in the fourth quarter.
Kowalski was signed as a guard, but offensive line coach Hudson Houck wants his group to play more than one spot on the line.
When Costa was hurt, Kowalski moved right in with no problems.
"Fortunately I had been getting quite a bit of reps at center during the week," Kowalski said. "Not so much at guard so the situation wasn't the worst situation that could have happened to me. I felt I was pretty prepared and the coaches helped me be prepared for the moment."
Costa, who said Kowalski did fine, said he's expected to be limited in practice this week. If Costa can't play, Kowalski may get his first NFL start vs. the Washington Redskins Monday night in the home opener.
"Either way, I have to be prepared," Kowalski said. "Obviously if Phil is there, he'll be our starter. If anything happens to him, I will have to go into the game and perform. I think it was good to me for me to get in my first NFL game and to perform."