The preliminary final was also notable for a horrific broken leg suffered by Nathan Cleary, which saw the star Penrith half taken to hospital while the game was still being played.
The Panthers also lost Blaize Talagi to a suspected ruptured Achilles tendon in the second half.
The tackle which caused Cleary’s injury late in the first half, when the score was tied at 6-6, resulted in Knights hooker Phoenix Crossland being sent off.
Talagi kicked the resultant penalty, and when the Penrith centre also converted Lindsay Smith’s 38th-minute try for an eight-point lead, virtually nobody would have bet on a Newcastle win.
Nathan Cleary left the field on a medicab after suffering a suspected compound fracture. Photo / Getty Images
Few expected the seventh-placed Knights to even get this far, advancing thanks to away wins over the Warriors 12-10 in Auckland and the Rabbitohs 20-10 in Sydney the previous two weeks.
But wing Dominic Young closed the gap with a try soon after the restart and halfback Sandon Smith gave Newcastle a shock lead with one of the cheekiest tries ever seen in the playoffs.
The Knights were awarded a penalty midway through the half on halfway, and with just about all the Penrith players turning their backs and switching off, Smith tapped and ran 50m through the entire opposition to score by the posts.
Only about three Panthers attempted a chase and even the initial television coverage missed most of his run.
Outstanding Newcastle defence then characterised the rest of the match, with the best tackle seeing Kalyn Ponga and Jermaine McEwen combine to stop Casey McLean grounding the ball by only a centimetre or two.
Smith struck again in the final minute, snatching an intercept and sprinting more than 80m for the converted try which wrapped up the most unlikely of wins.
That triggered floods of tears on and off the pitch as Newcastle – the club and city – could start looking forward to a first grand final in 25 years.