In terms of statistics, this was the Warriors greatest collapse.
On three previous occasions the Auckland team have forfeited an 18-point advantage to lose, but the 22 points was a new record.
It's a new low for the Warriors and will be hard to come back from. It might not be terminal, but this defeat will do a lot of physiological damage.
After their hard fought win over the Roosters - and two tough efforts in Canberra and Melbourne - it took only 40 minutes for the Warriors to encounter some familiar demons.
The Warriors made a near perfect start. They scored three tries in the first 20 minutes - which was their best start of the year and the most points they have scored in the first quarter of a match since the 2015 season.
Kieran Foran opened the scoring, forcing his way over after clever work from Issac Luke and Roger Tuivasa-Sheck to recover after a fifth tackle move almost broke down.
The Warriors' gained further momentum when Penrith winger Waqa Blake was sinbinned for 10 minutes for a professional foul. Blake had done well to haul in a try bound David Fusitu'a, but then held him down for way too long.
When Blake was off the field the Warriors added two tries; Charnze Nicoll-Klokstad finished off a sweeping backline play, then Ryan Hoffman split the defence with a trademark left edge run.
It was the Warriors best attacking period of the year so far - fast, fluid and functional, though the home side kept handing them the initiative.
After Isaah Yeo crossed for Penrith, the Warriors' fourth try was all down to Foran, and reinforced how much he will be missed next year. First he kicked a 40-20, then came up with a perfectly weighted grubber for Nicoll-Klokstad to finish off. It was a high percentage play - Foran's first priority was a repeat set - but the kick was good enough to snare the ultimate reward.
To top off a half where everything had gone their way, Fusitu'a grabbed an intercept to run 85 metres to score, shaking off another determined chase from Blake.
If the first half was a high, the second period quickly went sour. Penrith crossed for three converted tries in the space of 10 minutes, and the game was back in the balance. The Warriors looked edgy and nervous, and the Panthers successfully targeted Shaun Johnson on the right edge, with the halfback missing tackles for two Penrith tries.
It was scarcely believable, as the Panthers were seemingly scoring at will, and had taken the lead with more than 20 minutes seem to play, with captain Matt Moylan crossed for their fourth try of the half.
There were no real signs of resistance from the Warriors, who looked broken once the Penrith deluge started and a Tyrone Peachey try sealed the result in the 77th minute.
Warriors 28 (K Foran, C Nicoll-Klokstad 2, R Hoffman, D Fusitu'a tries, S Johnson 4 goals)
Penrith 36 (I Yeo 2, D Watene-Zelezniak, W Blake, M Moylan, T Peachey tries; N Cleary 5 goals)
Halftime: 28-6
