Head coach Jim Tomsula and special teams co-ordinator Thomas McGaughey declined to confirm if the Australian would be part of the active 46-man squad for Monday's (Tuesday NZT) game, but they also repeatedly worked to ease the massive amount of hype around the former NRL star.
They repeatedly pointed to how Hayne was a rookie and was still learning the game.
"I don't want to be the guy downplaying his accomplishments or the excitement for the country," Tomsula said.
Hayne has been pencilled in as the 49ers' third running back option and is grouped with Reggie Bush, DeAndrew White and Bruce Ellington as options for punt or kick returner.
The three players can contribute in other positions, with Bush as running back and White and Ellington as wide-receivers.
Tomsula said he was "very confident" in Hayne's ability to catch punts, but with the 49ers limited to just 46 players for a game he would have to contribute at other positions.
Hayne's skills would also have to suit the 49ers' gameplan for the Vikings.
Tomsula said Hayne still needed to work on aspects of being a running back, including pass protections.
"OK you can catch a punt, but can you do other things?" Tomsula asked.
When AAP jokingly told McGaughey Australia would declare war on San Francisco if Hayne was left out, he laughed.
"You know what, I'm aware of that," McGaughey, who has overseen Hayne's role as a punt and kick returner, said.
"No, Jarryd is a heck of a player, very talented, a young player, but needs to mature a little bit as far as getting experience."
While Hayne had earned his spot on the team's 53-man squad, the coaches repeatedly pointed to him being a rookie who still had a lot to learn.
They also said despite Hayne playing well in the four pre-season games, the regular season was different.
"We have to keep everything in perspective," McGaughey said.
"You have to understand the pre-season is the pre-season and right now is right now.
"This is real bullets.
"It was paintball."
Whether Hayne is on the 46-man squad for the Vikings will likely only be known 90 minutes before Tuesday's game.
