Just when the ladder-leading Panthers appeared unbeatable, maligned halfback Lachlan Galvin ignited the Bulldogs, who rode a 16-0 lead to victory as $6 outsiders.
Serious questions had been raised about the Bulldogs' attack during a 2-2 opening month, and halfback Galvin wore much of the criticism.
But the 20-year-old took on the bulk of kicking at home on Thursday night, flaunted his combination with Jacob Preston on the right edge and helped prove there's still plenty of life in the Bulldogs this season.
"(Galvin) was brilliant," said coach Cameron Ciraldo.
"He has to deal with a fair bit, Lachie, there are always questions asked about him but he's handled it great."
Galvin's one-two with Preston put the Bulldogs in position for their first try, before a flat pass to the second-rower restored the Bulldogs' lead after Penrith equalised at 16-16.
When Galvin put Preston into a hole and the NSW hopeful passed inside for Sitili Tupouniua to score, the Bulldogs went up 28-16 and were on the way to silencing their critics.
"We've had two poor halves of footy to start the season, and we're not the first team to come back from Vegas and not hit the ground running," Ciraldo said.
"The most pleasing thing for me is how much everyone within our four walls believed in what we were doing, stuck to our process."
Bronson Xerri also made an impressive return from his highly-publicised stint in reserve grade, throwing the last pass for Jacob Kiraz to give the Bulldogs a 10-0 lead after 11 minutes.
Penrith broke all sorts of records in the opening five weeks but proved they may be human after all.
Thursday night was their worst performance at full-strength since their form slump to begin last year.
"Rugby league is the ultimate leveller, it might be the best thing just to stop a little bit of that noise," co-captain Isaah Yeo said.
"People were talking about (us going) unbeaten through the season, that's certainly not the case now.
"Tonight we were a fair way behind, then it's just a different flow to the game to what it's been recently. That's not a bad thing, I think we'll be able to learn lessons from that."
The Bulldogs started fast to open the scoring through Viliame Kikau and Penrith were further on the back foot when Gerard Sutton retroactively sin-binned Casey McLean for a shoulder charge on Max King.
Nathan Cleary had a mostly unhappy 200th NRL game, despite a beautiful cross-field kick that helped Tom Jenkins confirm a sixth consecutive try-scoring double on the left wing.
Cleary's bad pass turned the ball over before the Bulldogs' first try, and at another point, he threw a pass much too high for Luke Garner to field near the touchline.
Dylan Edwards darted over from a scrum play as the Panthers made inroads on the 16-0 deficit, but the visitors gave up 15 errors and seven line breaks on their tough night.
Making matters worse for Penrith, second-rower Liam Martin did not finish the game and wore a brace on his knee after full-time
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