Before the regular season began, Marshall suffered a slight tear to his posterior cruciate ligament (PCL) in the preseason game against the Detroit Lions. Although the injury sidelined him for a couple weeks, he was able to return and play in 15 games (1 start) during the regular season. Marshall had a total of 20 catches, 309 receiving yards, and 2 touchdowns for his rookie year. On October 22, against the Cleveland Browns, he had his first professional receiving touchdown. He caught a pass in each of the Broncos' final seven games of the season, totaling 18 receptions, 287 receiving yards, and 1 touchdown over that stretch. The lone touchdown came during an NBC Sunday Night Football home game against the Seattle Seahawks on December 3, 2006. In that game, Broncos quarterback Jay Cutler (who was making his NFL regular season debut as a rookie) threw a pass to Marshall on the right side of the field. Marshall broke and spun away from three tackles on his way to a career-long 71-yard touchdown. It was the second longest rookie-to-rookie pass play in Broncos history.