Dynamic fullback Matt Dufty starred with two tries and two first-half assists for Jack Bird and Mikaele Ravalawa but the scoreboard didn't quite reflect a tough contest where Parramatta struggled to execute.
St George Illawarra's goal-line and scramble defence was outstanding as they displayed line-speed and aggression from the get-go, shocking the Eels and mounting an 18-0 half-time lead.
They overcame the sin-binning of Tariq Sims early in the second half, after which the hosts finally scored, to eventually kick clear.
"That's probably been just a feature of the last couple of weeks. We work really hard on our defence," coach Anthony Griffin said.
"They're just enjoying their footy at the moment. We’re not playing as well as you’d like all the time - that second half [for example] - but sometimes, particularly early in the year, you don’t have to. You have to get the basics right defensively and we did that for long periods.
"I don’t think we’re doing anything special. We’re doing what we need to do if we want to be a good football side."
Griffin said his team's attack for the opening 40 minutes was the slickest it's been. Dufty, who is finding a balance between exploiting space around the ruck and ball-playing on the edges, was the key.
But despite Dufty's performance, Griffin wouldn't be drawn on whether he'd seen enough from the pocket rocket and fellow off-contract star Corey Norman to make them retention priorities.
"[Dufty] is learning the real fine arts of playing fullback in tight football games like tonight," Griffin added.
"He needs to keep improving to unlock his potential."
A couple of debatable decisions went against the Eels.
The first was Dufty's 11th-minute penalty try after he broke clear from an Adam Clune inside pass and kicked ahead for himself, only to be knocked off course by Nathan Brown as he neared the in-goal.
The Bunker ruled the speedster would have won the race to the ball, much to the chagrin of the parochial Bankwest Stadium crowd.
Then with 13 minutes to go, Parramatta captain Clint Gutherson dived under the posts following a Dylan Brown bust but the Bunker deemed that Junior Paulo obstructed Tyrell Fuimaono in the lead-up.
Moments later, Clune split the line and provided Dufty with his double to seal the win despite Gutherson crossing at the end.
The Dragons boasted a completion rate of 90% in the first half, finishing the match at 83% after errors crept into their game.
A fifth-minute Gutherson mistake gave St George Illawarra a prime opportunity, with Bird claiming his maiden NRL try for his junior club and his first since 2019 after being put into a hole by Dufty.
The custodian added his name to the scoresheet with the penalty try and in the 32nd minute he threw a delightful left-to-right long ball for Fijian winger Ravalawa to produce a spectacular finish.
St George Illawarra were pinged for a plethora of ruck infringements to begin the second half – they committed nine compared to the Eels' five overall – but Parramatta didn't take full advantage.
Zac Lomax added a penalty goal to steady the ship after Papali'i's try and provide the visitors with a 14-point buffer.
Dragons players spoke earlier in the week about the squad’s tight-knit bond and that was apparent as they continually rallied to repel the Eels before their electric No.1 put the game to bed.