Dragons survived a late comeback from the Ospreys to hold on for 32-28 Magners League win on Friday.
The result seriously dents the Ospreys' chances of a home play-off semi-final at Rodney Parade.
Despite having nothing to play for, the Dragons had opened up a comfortable 32-11 lead over a lethargic away side but a fight back eventually brought the Ospreys to within four points.
Two tries from winger Aled Brew inspired the Dragons to the bonus-point before second half scores from wings Tommy Bowe and Nikki Walker nearly saw the away team snatch victory.
With neither team in European action last weekend, both sides came out with intent to play an attacking game. And the Ospreys opened up an early three point lead through a Biggar penalty but almost straight from the restart the play-off contenders were caught out by their over-ambitiousness.
From a turnover, number eight Toby Faletau and centre Ashley Smith exchanged passes which eventually saw Smith go over, with fly-half Jason Tovey converting.
The hosts' fly-half then extended their lead with two more penalties to take them five points clear.
Number ten Dan Biggar responded for the Ospreys with one of his own but the Dragons led 13-11 despite Tovey missing two late three pointers.
Newport pressed home their advantage in the early part of the second half when scrum-half Wayne Evans burrowed over, Matthew Jones converting, before Brew touched down. The winger then scored from another turnover to give the Dragons a seemingly unassailable 21-point margin.
But the Swansea-based side fought back. Firstly, Bowe scampered over before opposite winger Walker latched onto a cross-field kick. Replacement kicker James Hook converted both and added a penalty to leave them within an unconverted try of victory
For : Dragons
Tries: Smith, Evans, Brew 2
Cons: Tovey. M Jones 2
Pens: Tovey 2
Tries: R. Jones, Bowe, Walker
Cons: Hook 2
Pens: Biggar 2, Hook
Dragons: 15 Will Harries, 14 Adam Hughes, 13 Tom Riley, 12 Ashley Smith (c), 11 Aled Brew, 10 Jason Tovey, 9 Wayne Evans, 8 Toby Faletau, 7 Gavin Thomas, 6 Dan Lydiate, 5 Adam Jones, 4 Andrew Coombs, 3 Ben Castle, 2 Lloyd Burns, 1 Phil Price.
Replacements: 16 Steve Jones, 17 Dan Way, 18 Hugh Gustafson, 19 Lewis Evans, 20 Joe Bearman, 21 Matthew Pewtener, 22 Jon Evans, 23 Matthew Jones.
Ospreys: 15 Lee Byrne, 14 Tommy Bowe, 13 Andrew Bishop, 12 James Hook, 11 Nikki Walker, 10 Dan Biggar, 9 Rhys Webb, 8 Jerry Collins, 7 Marty Holah, 6 Tom Smith 5 Alun Wyn Jones (c), 4 Ryan Jones, 3 Adam Jones, 2 Huw Bennett, 1 Paul James.
Replacements: 16 Richard Hibbard, 17 Ryan Bevington, 18 Cai Griffiths, 19 Ian Gough, 20 Justin Tipuric, 21 Tom Isaacs, 22 Sonny Parker, 23 Richard Fussell.