The Western Bulldogs' man of the moment Bob Murphy has paid tribute to Sydney's injury-hit defender Alex Johnson, saying the man who has endured five knee reconstructions was a real hero.

Johnson, who has endured 12 knee operations since 2012 could return to the field in the NEAFL within the next two months after completing his first full training session - and without strapping on his knee.

"I started training and am probably only four to six weeks away from joining, which is something that just a few years I would have thought was almost impossible but it's getting closer now and I'm really excited." Johnson told SEN radio.

Johnson said that there were times when he despaired while training by himself in "the dungeon" under the SCG, but that the support of family, friends and teammates had encouraged him to stick with his football career.