The key to the victory was the Ospreys’ scrum, spearheaded by Wales props Duncan and Adam Jones. It created the opening touchdown for wing Aled Brew and then a penalty try just before half-time.
The boot of fly-half Craig Warlow had kept the plucky Dragons in touch throughout, but they just lacked the cutting edge at crucial moments. Warlow had given the Dragons an early 3-0 lead, but the writing was on the wall when the Ospreys shoved their Gwent visitors off their first scrum of the match.
Flanker Steve Tandy pounced on the loose ball and skipper Leigh Davies floated a perfectly weighted pass out to Brew who had a clear path to the corner. Fly-half Matthew Jones missed with the conversion, but landed a penalty soon after following some indiscipline from the Dragons eight.
The Dragons then had flanker Jamie Ringer sent to the sin-bin for killing the ball at a ruck but the loss did not seem to do them much harm as Warlow reduced the arrears with his second penalty success.
However, as the Ospreys took control of the game so the Dragons continued to fall foul of referee Nigel Whitehouse. Wales full-back Kevin Morgan was next to be shown yellow following a similar offence to Ringer and, although Hal Luscombe produced a magnificent cover tackle to deny Stefan Terblanche in the corner, the Ospreys claimed their second try just before the break.
It came again from a close-range scrum and, after awarding a string of penalties, Whitehouse’s patience eventually ran out when he awarded a penalty try.
Jones’s conversion made it 15-6 at the interval although the young Wales international then missed with a chance to increase his side’s advantage just after the restart.
In contrast, Warlow’s radar was spot on and he made 15-9 midway through the half after Ospreys prop Duncan Jones became the third player to be yellow-carded for slowing down possession.
It prompted some nervous final moments for the home fans and a breakaway by Luscombe five minutes into injury time almost snatched the game for the visitors. But they had to be content with a losing bonus point for their efforts.