The game was over with almost 30 minutes to play, after the Sea Eagles scored three tries in the space of six minutes after halftime. Manly plundered 26 points to six in the second half and the crowd had to endure the sight of Willie Mason taunting them.
A game that was meant to be a two-point banker - considering the form of the Sea Eagles - could prove to be a major turning point in the Warriors' season.
Manly scored six tries and could have had several more, while the home side barely fired a shot in their fourth loss at Mt Smart this season.
Sure, there were mitigating factors, especially the loss of Johnson, who was in agony after injuring his left leg when scoring a first-half try and was soon taken away in an ambulance.
Bodene Thompson (ankle) also left the field midway through the second half. But the Sea Eagles lost three players to injury in the first half alone, including a nasty concussion of Steve Matai in the first quarter and had no one on their bench in the last 20 minutes of the match.
What was most disappointing was the lack of will, fight, hunger, desire - call it what you want, it just wasn't there.
The club cut some players during the week but some who were on the field tonight will be looking over their shoulders.
The Warriors should have had plenty to play for. There was the top eight, redemption after last weeks' humbling and it was old boys day at Mt Smart, when more than 40 former players were honoured.
Meanwhile, the Sea Eagles were supposed to be playing only for pride, their season all but over and the club in disarray, with unconfirmed reports of 14 players and coach Geoff Toovey being cut.
But this is Manly and there are two irrefutable truths about the team from the Northern beaches. They thrive on adversity - always have - and they are usually Kryptonite for the Warriors.
The Auckland club had won just two of the past 10 clashes, and had enjoyed only four victories across the last decade. They seem to have a psychological hold over the Warriors, perhaps since that infamous game in Perth in 2012. It was a flat start from the Warriors.
They couldn't get anything going, stunted by static attack, cheap penalties and mistakes. Manly took a deserved lead in the 10th minute, Jake Trbojevic profiting from a remarkable Ligi Sao offload. A few minutes earlier Ben Matulino had freed his arms near the posts but had no support runners - which summed up the lack of urgency from the home side.
The Sea Eagles had further chances before Johnson's moment of magic, which will be his last for a while. The halfback stepped through the Sea Eagles defence before dragging three defenders across the line with him, but his right leg was trapped in the process.
He left the field in obvious agony, and was taken to hospital for scans on his ankle. In his absence the team fell apart, with a series of soft tries as Manly plundered the right edge at will.
Warriors 12 (S. Johnson, A. Vete tries; T Lolohea 2 gls)
Manly 32 (J. Trbojevic, J. Taufua 2, B.Stewart 2, M. Ballin tries; J Lyon 4 gls)
Halftime: 6-6
