Mark this down as one of the worst Warriors losses of the season.
That's a big call – given some of the defeats we have witnessed in 2019 – but this one will be hard to stomach.
A James Maloney field goal condemned the Warriors to a 19-18 loss in golden point, after the home side had led 16-12 with less than three minutes to play, before Panthers centre Brent Naden busted through some ineffective tackles and ran 85 metres to score.
"[It's a] hard one to take...there is no doubt about it," said Warriors coach Stephen Kearney. "There were some huge efforts out there and we got a reminder that when the moment presents itself, you have to get it done. At the back end we had a couple of fellas that didn't do it, in terms of a missed tackle. That was the moment. With two and half minutes to go we could have nailed it."
The Warriors were looking for their first win at Mt Smart in three months, but instead continue an awful streak, without a victory in Auckland since round four.
Penrith had two periods of being reduced to 12 men, missed more than 50 tackles and lost the penalty count 11-5 – but found a way to stay in the game.
"[At times] we probably had every reason to pack it in for the night and we haven't travelled well throughout the season…just a brave win," said Panther coach Ivan Cleary.
To compound the Warriors misery, luckless hooker Nathaniel Roache limped off late in the second half with a suspected ACL injury.
The Warriors were guilty of not putting the foot on the throat, when ahead 16-6 early in the second half, with the Panthers a man down, and paid the ultimate price.
It was a scrappy game, full of mistakes, exactly what you might expect from two teams that have struggled this season.
The Warriors were far from polished, with some clunky attack, but they at least showed some desire. There was a willingness to put their bodies where it hurts, and for the most part worked hard defensively, unless they lost concentration late.
The Warriors had opened the scoring through Peta Hiku, who showed impressive dexterity to get the ball down, after interplay from Jazz Tevaga and Karl Lawton had created some momentum.
But Viliame Kikau was causing havoc. The 1.95m, 119kg Fijian international gave an ominous sign of his intentions in the first set of the match, as he bowled through two defenders to make 30 metres.
Another tackling busting run – where he rampaged over both Warriors centres, gave the Panthers field position and they eventually profited, with Maloney's quick thinking after a kick rebound setting up James Tamou to stroll over between the posts.
The first half had errors galore, but the Warriors were the better of two misfiring teams. They drew level with a penalty after incessant pressure, with the Panthers chipping "That's a win for us boys" after the home side elected to take the two.
Lawton went close from dummy half, before the Panthers were reduced to 12 men, with Liam Martin sinbinned after a string of penalties.
The Warriors were quick to take advantage, as Roache's no look pass found Bunty Afoa, who forced his way over from close range for his 5th NRL try in 57 games.
Naden was agonizingly close to a remarkable try, after a sequence that featured three kicks from the Panthers and some casual Warriors defence.
The home side have copped some rough decisions this year, but were beneficiaries of a strange one early in the second half, after Jarome Luai was sinbinned for taking out Roger Tuivasa-Sheck. He did appear to block the Warriors fullback, but wasn't worth more than a penalty.
It was exacerbated after the Warriors scored in the next set, with Fusitu'a flying through the air like only he can, with a miraculous put down.
Then followed an all too familiar Warriors fade, as energy and intensity dipped, allowing Penrith to take the initiative, and Naden soared to claim a Maloney kick above Tuivasa-Sheck.
The Warriors were hanging on, and looked to have done enough, having pinned the Panthers deep in their own territory, before Naden busted through Herbert and Fusitu'a and sprinted away to score. Just when all seemed lost, the Warriors won a penalty from the kickoff, and Herbert showed remarkable composure to kick a tricky penalty on the angle from 35 metres.
But Penrith always looked more likely in the additional period, and Maloney coolly nailed his second attempt.
Panthers 19 (Brent Naden 2, James Tamou tries; James Maloney 3 cons, field goal)
Warriors 18 (Peta Hiku, Bunty Afoa, David Fusitu'a tries; Patrick Herbert con, 2 pens)