Coach Andrew McFadden confirmed Johnson's season-ending injury was two-pronged - with the number seven undergoing surgery this morning - but is backing his side to overcome the loss of their key playmaker.
Scans established the 24-year-old had fractured his fibula and suffered ligament damage. He has had a plate inserted as well as two syndesmotic screws.
"I spoke to the doctor last night and I spoke to Shaun. He's got a fracture of his leg, he's done some damage to his ankle as well with some kind of slight dislocation there," McFadden told Radio Sport today.
"So he's got a bit of work to do on it and it's certainly season-ending and it's going to be a fairly lengthy rehab as well.
"It's certainly going to make it more challenging. He is a key player for us and he's been playing terrific football and really he's been the person that brings us all together.
"But we do practice without Shaun. Sometimes he doesn't train so we're going to have to fall back on those combinations. It may take a little while but hopefully not too long."
The Warriors troublesome right-edge may need to be completely revamped; with back-rower Bodene Thompson expected to miss at least a couple of matches after he succumbed to an ankle injury in the final quarter.
Going into yesterday's match, the right edge was already without first-choice centre
Konrad Hurrell, while winger Glen Fisiiahi had his first NRL game in 15 months back on the flank that has also been home to Tui Lolohea, Ken Maumalo, and Jonathan Wright.
"He's (Thompson) got a minor ankle injury at the moment so it looks like he'll miss a couple of weeks at least so that's disappointing again," said McFadden.
On the bright side, left-edge back-rower Ryan Hoffman is expected to return for Saturday's home game against the Cronulla Sharks, after missing the last two defeats to the Sydney Roosters and Sea Eagles, while Hurrell is also available after serving a one game suspension.
Rookie utility Tui Lolohea, who started at centre against Manly before shifting in one place to cover Johnson's absence, or fullback Sam Tomkins, are the obvious options to partner current five-eighth Chad Townsend in the halves as the Warriors look to steady the ship and maintain their fight to stay in the top eight.
"We've obviously got Tui Lolohea there," McFadden said. "We'll just have to play around with that to see what the best dynamic is.
"Obviously Sam Tomkins has got a ball-playing ability so whether we put Tui to fullback and Sam into the halves, or some sort of combination of the two, so we've got a few options there.
"It will just come down to the best balance for the team."
McFadden agreed Johnson's plight may present the opportunity for Tomkins to stand up and steer the Warriors through the final six weeks of the regular season and his last games for the club before the England international returns to Wigan to play in the UK Super League.
"He has to. We've got no choice with that. Losing someone like Shaun and how important he is to our team, if he's going to be out of our team then people have to step up.
"We've got to draw a line in the sand and some of these guys are going to have to do something special.
"And Sam's one of those guys and he's very capable of it so certainly I know he'll be very keen to do that.
"We're not throwing the towel in. We're in a bit of a tough spot at the moment but with some good hard work we can get ourselves out of it."
