"I just remember playing the game and going towards the try line and feeling my leg go," said Johnson. "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 and the road to recovery starts now as he left hospital today.
"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. An emergency case came in so I had to wait until the morning but it's all done now."
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 put in 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.
"I'll take it pretty easy in the next few weeks but once I'm in rehab, I want to strengthen it up. I'll be talking with our coaching staff and I know Ruben Wiki is pretty excited to see me in a couple of weeks. He'll certainly put me through my paces.
"It's four to five months before I'll be able to run fully and freely. That's a challenge in itself already and I want to try and beat that. I want to get moving as soon as I can but I want to be smart about it.
"I don't want it to be the sort of injury that hangs over me for the rest of my career."
The Warriors have dropped to eighth on the ladder and they face one of the NRL's form teams this weekend as Cronulla Sharks visit Mt Smart.
They've won their last three and leapfrogged the Warriors into sixth place but Johnson still believes they can make something of this season.
The question on everyone's lips is what combination Andrew McFadden will have at halfback in Johnson's absence.
"I'll certainly be in and around the boys as much as I can," said Johnson. Cappy's got a few options. When I was fit we trained with different combinations all the time.
"If I was out or Sammy Tomkins or Chad, anyone could come in and fill that role. We're blessed that we can prepare for that.
"I'm really gutted that I'm out but I don't want anyone to lose faith in the side and think the season is over.
"The weekend was a bit of a setback for us but with the players we've got, they won't settle for anything less. Everyone out there should stick with the boys."
