Lolohea will join Chad Townsend in a new halves combination to face the Cronulla Sharks after Johnson was ruled out for the season after suffering a broken fibula and partially dislocated ankle in the loss to Manly last weekend.
Johnson spoke yesterday for the first time about the injury. He said he felt "a yuck feeling" as he suffered the injury which will sideline him for four to five months.
In an interview with Warriors TV, Johnson recalled what happened and remained upbeat about his return as well as the Warriors' prospects for the rest of 2015.
"I just remember playing the game and going towards the try line and feeling my leg go," he said. "Someone came down on it and I sort of had a yuck feeling.
"When the pain hit me I knew something was wrong. I got taken under the stand and the doctor looked at me. That was me done. I had to wait until half time before I could get across the field and get in the ambulance.
"I didn't get to watch the game but I remembered to check the score when I was in the ambulance on the way to hospital. I saw the scoreline and I was pretty disappointed. I know how gutted the boys would have been."
It's the first serious injury Johnson has had since he made his NRL debut in 2011.
"This one's right up there. It's the worst one I've had to go through," he said.
"I've been really lucky with the run I've had. I've had a few little minor injuries and with the coaching staff we've got, I've been able to manage it.
"It's pretty sore but then they put me on all sorts of meds and it took the pain away. I was able to get through it so I was all good.
"I was lucky to be looked after so quickly. I had the x-ray and I was able to have the surgery straight away."
Johnson confirmed his surgeon was happy with the operation he had on Sunday morning and he'll now be in a plaster for 10 days before he gets a moon boot.
The 24-year-old is already talking up his comeback trail as he bids to return to full fitness in time for the 2016 NRL campaign.
The 21-year old Lolohea has already started at fullback, in the centres and on the wing this season, but now gets the nod as the fulltime number seven after spending 55 minutes in the role against Manly once Johnson left the field.
"Tui was a natural choice in the halves. He has trained there throughout the season when Shaun and Chad have missed training sessions," said McFadden.
Although Johnson's absence is the biggest blow to the side, McFadden has also been forced to make changes in the back row with Bodene Thompson out with an ankle injury and Ryan Hoffman not yet recovered from his calf complaint picked up in the final State of Origin match earlier this month.
As a result, captain Simon Mannering is moved from loose forward to operate on the edge with Ben Matulino switching from prop to start in the second row.
Sebastine Ikahihifo will take over in the number 13 jersey after an impressive display in the New South Wales Cup last weekend.
