Penrith are one win away from their first grand final in 17 years after a Nathan Cleary masterclass made the Sydney Roosters' shot at a three-peat even more difficult.
Cleary scored a first-half hat-trick and kicked a crucial field goal as the Panthers held on to win 29-28, putting pay to a second-half comeback from the two-time defending premiers.
And while Cleary finished with points, halves partner Jarome Luai was just as good in his first finals match with a hand in four of Penrith's five tries.
It took their winning streak to 16, making for the third biggest of all-time.
But it wasn't all smooth sailing for the Panthers, with Viliame Kikau facing a possible ban for a dangerous tackle that threatens his preliminary final availability.
For the Roosters, they must now do it the hard way via a sudden-death semi-final between the winner of Canberra and Cronulla.
After Penrith led 28-10 with 27 minutes to go, the Roosters scored two tries in 11 minutes through James Tedesco and Josh Morris to put themselves back in the match
A field goal from Clearly looked as if it would seal the match with two minutes to play at 29-22, but Penrith gave away a penalty from the kick off and Angus Crichton scored.
The Panthers were able to hold on, with Liam Martin making a last-ditch tackle on Morris and Kikau getting a finger on a 40-metre field goal attempt from Luke Keary.
"I could feel the energy in the group that we were coming back," Roosters coach Trent Robinson said.
"I knew that we were coming, I knew we'd win the second half. We just needed to keep on it and keep on it.
"We just ran out of time."
While Jared Waerea-Hargreaves finished the match on report, the fightback at least gave the two-time defending premiers a much needed boost after last week's flogging from South Sydney.
They will also likely have Sonny Bill Williams (neck) and Jake Friend (concussion) back next week, where if they progress they face the winner of Melbourne and Parramatta in week three.
Meanwhile the match's finale wasn't the first time the Panthers had to rally.
After Morris and Freddy Lussick scored early, Penrith were facing their biggest deficit since they were forced to come from behind to shock the Roosters in round one.
Spending just 74 minutes behind on the scoreboard in their 1450 on the field since the competition's restart, it was fair to ask if Penrith would have the answers.
But when it mattered they had more than enough.
It began in defence when Josh Mansour, Luai, Edwards and Stephen Crichton ganged up to force Morris over the sideline.
From the second tackle off the scrum, the Roosters were caught offside. And from there, it was all Penrith.
Mansour scored first when Luai and Kikau combined, before Cleary chalked up his three tries.
The highlight was his second, diving through on a Luai grubber to grab it in front of Tedesco and score.
And when Luai batted back a Cleary bomb after the break for Tyrone May to put Stephen Crichton, the game looked over before the Roosters' near comeback.
"The heart was racing a bit for sure," coach Ivan Cleary said.
"There were questions of how we were going to handle the semi-finals and I think the start and the end showed that