SYDNEY forward Gary Rohan has been ruled out until at least round four with back soreness.

The Swans announced on Friday afternoon Rohan would make a delayed start to the 2017 home and away season, with the 25-year-old having been put on the club’s long-term injury list along with Alex Johnson.

Swans football manager Tom Harley said Rohan had missed a significant portion of pre-season training because of several niggling injuries.

"Gary has been limited in his training, most recently because of back soreness," Harley said.

"As a result of his limited training, he will need at least another eight weeks of preparation before he can return to play.

"Gary had a similar start to last season and was still able to come in and make a significant impact, so we're confident he will do the same again this year."

Harley said Johnson's rehabilitation from his fifth knee reconstruction was progressing well.

"We're really pleased with where Alex is at in terms of his rehabilitation, he's been gradually increasing his training and is in great spirits," Harley said.

"By placing Alex on the long-term injury list it will enable him to be available for selection from round four, and we're really hopeful of seeing him return to playing this year."

Johnson played every game in the Swans' 2012 premiership season as a second-year defender, but his knee woes have sidelined him ever since.