One of the great NFL careers, and one of the most significant careers in Colts history, is coming to a close.

Indianapolis wide receiver Marvin Harrison, who did not make the trip to Jacksonville for tonight’s game against the Jaguars due to a knee injury, could well be playing his final season with the Colts.

Next season, Harrison’s is scheduled to carry a $13.4 million salary-cap number for a Colts team that already is $2.5 million over the 2009 salary cap. In a year when it’s going to be more difficult than ever to restructure contracts because none of the money can be pushed into 2010 when there is no salary cap, Indianapolis and other teams are going to struggle to find salary cap room.

Yet the 36-year-old Harrison, an eight-time Pro Bowl selection, could almost singlehandedly provide it for the Colts. If Indianapolis were to release Harrison after this season, his $13.4 million salary-cap number would come off the books and he would save the team $7 million against the cap. He still would count $6.4 million in dead money, but more important, there would be a $7 million savings.

And it’s not like the Colts haven’t been grooming receivers for Harrison’s eventual departure. Two years ago, Indianapolis invested a first-round pick in wide receiver Anthony Gonzalez. The team also is pleased with the progress that young receivers Roy Hall and Pierre Garcon have been making.

Harrison has been so good for so long, but in the NFL, even the great careers eventually get sidelined. All the signs now point in one direction — to the team moving in another direction.