Problem was the defender was coming on a full sprint (Minus the small block/run over from the kicker) and Romo had to start from a complete standstill..... He never had a chance to get up to speed.
Now I dont think Romo realized he could get a first down. I think he thought he had to score. If he knew he only needed to get inside the one, you have to think with 4 guys closing in, he would have dove...
Sean