Canterbury have confirmed their first top-four finish since 2012 but an injury to Jacob Kiraz soured their 28-4 defeat of Penrith, who fielded the least experienced team ever seen in the NRL era.
Superstar winger Kiraz landed awkwardly on his left ankle fielding a kick late on Thursday night and needed assistance leaving the field at Accor Stadium.
Kiraz could eventually hobble without support from trainers but early fears are that he has suffered a syndesmosis injury.
The 23-year-old came close to a NSW Origin debut this year and would be a significant loss for the Bulldogs as they fight for their first premiership since 2004.
If Kiraz is unavailable, either journeyman Enari Tuala or rookie Jethro Rinakama would need to be called into the third-placed Bulldogs' 17 at the most important point of the year.
Second-rower Jacob Preston scored the first hat-trick of his NRL career to help the Bulldogs kick clear after some resistance from the unrecognisable Panthers in the first half.
With an eye on finals, Ivan Cleary rested all but one man from the Panthers' last game, playing a side with only 398 games of first-grade experience and four debutants.
That number went to five when 18th man Jaxen Edgar was activated following game-ending concussions to Luke Sommerton and Sione Fonua.
But the Panthers showed the defensive grit of their regular first-graders as they repeatedly repelled the Bulldogs, whose red zone fifth tackle options were particularly poor.
Lachie Galvin put Josh Curran into space and then supported him for their first try, before a shift put Preston over for a 10-0 half-time lead.
Galvin put Preston in for his next two tries, with the second-rower breaking through three tackles on the way to his third.
Amid a form slump for regular fullback Dylan Edwards, off-contract Daine Laurie was Penrith's best, helping hold Sitili Tupouniua and Connor Tracey up over the line in consecutive tackles at one point.
In the second, he threw the bullet-like pass for Paul Alamoti to score the Panthers' only try.
But Penrith, for their grit in defence, never appeared a serious threat of piling points on, unable to create consistent opportunities or spend extended time up the other end of the park.
The Bulldogs are now guaranteed to finish either third or fourth, but leaping into the top two appears a bridge too far given Melbourne's superior points differential.
Last on the ladder after 12 rounds, the Panthers can finish the regular season as high as fifth but seventh or eighth appears likelier.