Jarryd Hayne has showed his San Francisco 49ers' teammates something NRL fans and opponents have known for years.
"A phenomenal athlete," is how the 49ers' quarterback Colin Kaepernick, who a year ago signed a six-year, $US114 million ($A148 million) contract, described Hayne in a rave review.
"Just a natural."
The 49ers released footage on Friday (Saturday AEST) from the first week of their workouts at the NFL team's practice facility built alongside the team's $US1.3 billion ($A1.69 billion) Levi's Stadium.
The video shows Hayne in a white 49ers training shirt blitzing many of his teammates in sprints and drills and giving a high-five to team leader Kaepernick, who first met the Australian last month at a high-performance training facility in Arizona.
The 27-year-old, heavily-tattooed Kaepernick is also a freakish athlete who played elite high school basketball and looked set to be drafted by a Major League Baseball team as a pitcher before being recruited by the University of Nevada football team.
While Hayne hasn't played a single NFL game, Kaepernick, who has been playing American football since he was eight, has no doubt the former Parramatta Eel has the talent and work ethic to succeed in the US.
"Since the day I've met him, since every workout he's been at, he's going to give you everything he has," the quarterback said.
The big question mark hanging over Hayne has been how quickly could he learn the complex NFL game.
"It doesn't seem like there's much of a learning curve for him," Kaepernick said.
As for where Hayne, who could potentially play running back, punt returner, wide-receiver or a defensive position, would end up on the field, the quarterback said it was up to the 49ers.
"This is going to be a football player," Kaepernick said.
"He does a lot of things very well and it's going to be our job to be able to utilise him and put him in position to allow him to make plays and use that athleticism."
Hayne believes he has about 20 weeks to impress the 49ers' coaching staff.
The team has 90 players, but will cut the roster to 53 in September on the eve of the 2015-16 season.
They will also have an eight-man practice squad that Hayne is favoured to be signed to.
