Nelson started the 2005 season against FIU. Against the Golden Panthers, he had four receptions for 36 yards. He caught his first career collegiate touchdown, an eight-yard pass from quarterback Allen Webb, in the game. Including the season opener, Nelson caught a touchdown in seven straight games that he appeared in. In that seven-game stretch, Nelson's best performance came against Oklahoma in a game where he had three receptions for 107 yards and a touchdown, which was a 73-yard reception from Webb. Kansas State struggled down the stretch of the season and did not make a bowl game. In the final game of the season, Nelson had seven receptions for 74 yards and a touchdown against Missouri.