Defending champions Northampton took advantage of a hapless Dragons scrum to claim a 28-3 LV= Cup victory at Franklin's Gardens.
The visitors lost three front-row players to the sin-bin during the course of the game, resulting in uncontested scrums.
The Saints had the better of the opening exchanges and took the lead after five minutes when Stephen Myler kicked a 25-metre penalty.
After 15 minutes, full-back Pat Leach knocked on a high kick and at the resulting scrum the Dragons collapsed and were again punished by Myler's boot.
The Saints totally dominated the opening quarter but decent defence from the Dragons somehow kept their line intact, although centre Jon Clarke did them a big favour by dropping the ball with the line at his mercy.
But the visitors' scrum was conceding penalties at almost every set-piece and eventually the patience of referee Sean Davey was exhausted after 32 minutes and he sent Dragons' prop Dan Way to the sin-bin.
Not surprisingly Northampton chose another scrum instead of kicking the penalty and it paid dividends with the first try of the game.
Again the visitors went backwards and Ryan Powell had little problem in sending Paul Diggin over in the corner for the try.
On a very rare excursion into the Saints' 22, the Dragons earnt a penalty which Matthew Jones knocked over.
The Dragons suffered a further blow when captain Steve Jones left the field with an injury moments before the interval, with his side 11-3 behind.
The visitors brought on first-choice half-backs Jason Tovey and Wayne Evans for the second half, but within two minutes of the restart Myler had extended the Saints' lead with another penalty.
Tovey missed a penalty for the Dragons before they lost replacement hooker Lloyd Burns to the sin-bin, leading to uncontested scrums.
Calum Clark immediately drove over for a try which Myler converted before the outside-half dummied over for another score, adding the extras himself to make it 28-3.
Nigel Hall came on as a replacement prop for the Dragons and at his first scrum was yellow-carded for twice collapsing the set-piece.
However, despite all their pressure, the Saints could not score a fourth try and claim the bonus point.
Tries: Diggin, Clark, Myler
Cons: Myler 2
Pens: Myler 3
Pen: M Jones
Northampton: 15 Shane Geraghty, 14 Joe Ansbro, 13 Jon Clarke, 12 James Downey, 11 Paul Diggin, 10 Stephen Myler, 9 Ryan Powell, 8 Mark Easter, 7 Phil Dowson (capt), 6 Calum Clark, 5 Christian Day, 4 Mark Sorenson, 3 Brian Mujati, 2 Brett Sharman, 1 Soane Tonga'uiha.
Replacements: 16 Andy Long, 17 Alex Waller, 18 Tom Mercey, 19 Dan Sanderson, 20 Tom Wood 21 Stuart Commins, 22 Joe Ford, 23 Jamie Elliott.
Dragons: 15 Pat Leach, 14 Tom Cheeseman, 13 Tom Riley, 12 Rhodri Gomer-Davies, 11 Aled Brew, 10 Matthew Jones, 9 James Leadbeater, 8 Toby Faletau, 7 Lewis Evans, 6 Hugo Ellis, 5 Rob Sidoli, 4 Adam Jones, 3 Dan Way, 2 Steve Jones, 1 Hugh Gustafson.
Replacements: 16 Lloyd Burns, 17 Nigel Hall, 18 Pat Palmer, 19 Luke Charteris, 20 Jevon Groves, 21 Wayne Evans, 22 Jason Tovey, 23 Ashley Smith.
Referee: Sean Davey