The Detroit Lions and San Diego Chargers had also shown interest in Hayne, but the 49ers were the only franchise to offer him a contract guarantee of US$100,000 ($128,000).

The 27-year-old made the announcement at a press conference in the Sydney CBD on Tuesday, five months after he quit the NRL to purse his dream of playing in the NFL.

‘‘It feels surreal,’’ a noticeably bigger Hayne said.

‘‘This is a small step in the right direction, it all starts now.’’

‘‘Mentally I’m ready to do anything it takes.

‘‘It’s a massive leap of faith.’’

Hayne said that 49ers team management had indicated running back was his likely position.

‘‘I just have to get over there and get into it ... a running back is what they see me as,’’ he said.

‘‘It depends on how I go. We will just have to wait and see.’’

Hayne will return to America later this month before officially starting training with San Francisco on April 10.

‘‘I honestly don’t know what to expect,’’ he said.

‘‘No one has ever done this before.’’

‘‘I’ve got 15-20 weeks of training to show what I can do.’’

He said he thought until recently that he would be going to the Lions. ‘‘It was very close but it wasn’t to be.’’

Hayne said he initially rejected the possibility of doing a work out for the 49ers.

‘‘They were about to lose their head coach (Jim Harbaugh) from all media reports and the plan was to go to a stable environment.

‘‘There were a lot of question marks, but I said I’d go. I ended up meeting Jim Tomsula the current head coach, and we spent about an hour together.

‘‘He was the one coach who knew the transition better than anyone and knew what it was going to take for me to make the transition.’’

Having coached NFL in Europe, Tomsula has worked with rugby union players and Hayne said that connection and understanding impressed him.

The rookie contract gives Hayne a spot on the 49ers 90-man roster, with the chance to make it onto the 53-man roster for the NFL season proper.