 Christensen was selected in the second-round (56th overall) of the 1978 NFL draft by the Dallas Cowboys.While playing fullback and leading the team in rushing, he broke his foot in the final exhibition game, so he was placed on injured reserve and couldn't play a down in a season the team won the conference title and played in Super Bowl XIII.The next year the Cowboys wanted to convert him to tight end, but he didn't agree with the move after working one week in his new position, so he was waived at the end of training camp.