The Eels led 16-0 after just 11 minutes to silence the 36,289 fans at Suncorp Stadium before the Broncos regained their composure under the leadership of Reynolds to roar back into the match.
Sailor raced 60m to get the Broncos on their way in the 31st minute and after his side went to the break down 16-12, set up the first try of the second half with a cut-out pass to winger Selwyn Cobbo
Reynolds swooped on a loose Eels pass in the 66th minute to put the Broncos ahead for the first time before a delicate kick for centre Kotoni Staggs had the hosts up 30-18.
Eels forward Shaun Lane scored in the 73rd minute to set up a tense finish.
Josh Rogers scored to put Brisbane firmly back in contention at halftime. (Jono Searle/AAP PHOTOS)
The victory takes the Broncos to 26 points, just two behind St George Illawarra, who host Cronulla on Sunday.
To play finals Brisbane must win both remaining games against the Dolphins and Melbourne and hope the Dragons win no more than one of their three matches.
Parramatta started on fire with fullback Clint Gutherson sending centre Will Penisini through a hole left by a poor defensive read by Deine Mariner.
Gutherson threaded a superb grubber through for Joe Ofahengaue to pounce and make it 12-0.
Winger Maika Sivo scored soon afterwards and Brisbane's finals hopes appeared dead.
Adam Reynolds was inspirational for Brisbane with a try and five conversions. (Jono Searle/AAP PHOTOS)
Sivo saved one try with brute strength by throwing Sailor over the dead ball line, and then another by beating Staggs to an Adam Reynolds grubber kick.
A scintillating run by Broncos fullback Tristan Sailor lit up Suncorp Stadium. From a standing start the St Helens-bound flyer blitzed the Eels defence to score his first try in the NRL since 2019.
Five-eighth Josh Rogers dummied and stepped his opposite number Dylan Brown three minutes later.
The visitors had their chances in the second half but it was the class of Reynolds, the blockbusting running of Cobbo and another warhorse display by lock Pat Carrigan that carried the Broncos to victory.
Parramatta's loss ensured they would play for the wooden spoon in a fortnight when they meet with Wests Tigers.
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