Warriors captain Roger Tuivasa-Sheck inspired his team to an historic 18-12 win at WIN Stadium against St George Illawarra to all but guarantee the New Zealand-based team's first finals appearance for seven years.
The Dragons scored the only points of the second half but were not able to overcome the loss of NSW State of Origin prop Paul Vaughan in the 11th minute with an ankle injury and the 29th minute sin-binning of fullback Matt Dufty.
The loss of Dufty for a professional foul after grabbing at the shorts of Tuivasa-Sheck while chasing a grubber kick from the Warriors fullback proved costly as the visitors scored three tries while he was in the sin-bin.
Tuivasa-Sheck also saved a certain try at the other end in a return to form for the Warriors skipper, who troubled the Dragons' defence every time he touched the ball.
He ran 239 metres with the ball and made two line breaks as well as nine tackle breaks.
The win was the first time the Warriors had beaten St George Illawarra at WIN Stadium and just the club's second victory in Wollongong after beating the Illawarra Steelers in 1996.
Match: Dragons v Warriors
Round 21 -
Venue: WIN Stadium, Wollongong
It was the Dragons' fourth loss in the last five games and puts them in danger of dropping out of the top four for the first time this season.
The Dragons dominated the opening exchanges but errors proved costly, with Tyson Frizell passing to Warriors hooker Issac Luke after breaking into the clear and Cameron McInnes dropping the ball on the try-line after a dummy-half run.
Winger Jordan Pereira appeared set to score in the 15th minute after stepping infield off a long Dufty pass but was stopped short by a high shot from Gerard Beale, who forced a knock on from Gareth Widdop with another big hit in the set of tackles following the penalty.
The decision for Shaun Johnson to opt for a 20th-minute penalty goal was an indication that the momentum still favoured the Dragons but that shifted immediately after Dufty's sin binning.
Warriors centre Solomona Kata scored just three tackles later after an offload by second rower Isaiah Papali'i and things went from bad to worse for the Dragons as James Graham was forced from the field for a Head Injury Assessment while Johnson lined up the conversion.
Luke scored in the 34th minute after another offload by Jazz Tevaga to extend the Warriors lead to 14-0 before Tuivasa-Sheck produced the biggest play of the half when he stripped the ball loose from Dragons centre Tim Lafai in his own in-goal to save a certain try.
As Dufty stood on the sideline preparing to return with Graham, who had been cleared of a concussion, Kata crossed for his second try to put the Warriors ahead 18-0 at half-time and on track for their first win in Wollongong in 22 years.
The Dragons came out firing in the second half and capitalised on back-to-back David Fusitua errors, with McInnes scoring from dummy-half after he was bundled into touch and Luciano Leilua pouncing on a Widdop grubber following a knock-on by the Warriors winger.
However, they were unable to breach the Warriors defence again and the errors which plagued St George Illawarra in the first half returned late in the match to cost them dearly.
News & Notes... The Dragons were 9-0 at home after 17 rounds but have now lost their past two home games, to Wests Tigers in round 18 and Warriors in round 21... Prop Paul Vaughan has played 19 of the Dragons' 20 games in 2018, only missing round 17 when he was on Origin duty, but he could be in serious doubt for next week with a leg injury... Crowd: 13,924.