Gloucester crashed to their first defeat of the season after they were grounded by a Gavin Henson-inspired Ospreys in the EDF Energy Cup opener.

The west country club's impressive Guinness Premiership form - three wins and a draw from four starts - counted for nothing as two early tries and some pinpoint Henson goalkicking left Gloucester floundering at the Liberty Stadium.

Head coach Dean Ryan had been confident about his team's ability to withstand wholesale changes, but the Ospreys emphatically mocked his theory.

Centre Sonny Parker claimed a quickfire try double just after half-time, securing a bonus point for the Ospreys following opening touchdowns by wing Shane Williams and hooker Barry Williams.

Fly-half Henson compounded Gloucester's misery by amassing 24 points, including a try, while ex-All Blacks star Justin Marshall galloped over from 40 metres to underline the rout.

The only worrying note for a rampant Ospreys side came when number eight Ryan Jones limped off midway through the second period.

Wales international Jones, a Lions tourist last year, missed the whole of last season with a shoulder injury and is an integral part of national coach Gareth Jenkins' autumn Test plans.

Gloucester managed a Peter Richards try and 14 points from Ludovic Mercier, but they were hopelessly outclassed in all key departments as their hopes of reaching the Millennium Stadium semi-finals next March spectacularly nosedived.

Gloucester fielded seven of the side on starting duty against Northampton last weekend, including former Ospreys hooker Mefin Davies, while their replacements' bench featured international trio Richards, Marco Bortolami and Olivier Azam.

The Ospreys were unbeaten at home this season, but they faced Gloucester on the back of a 43-7 Magners League thumping against Ulster in Belfast.

It took the home side just 62 seconds though, to breach Gloucester's defence as slick passing between backs and forwards saw full-back Lee Byrne send Williams sprinting over.

Henson drifted his touchline conversion attempt narrowly wide, but Gloucester found it tough early going matching an Ospreys side intent on a high tempo.

And the Ospreys' admirable approach gained another reward inside 15 minutes after Henson sacrificed a kickable penalty by booting possession into touch.

Ian Evans won the resulting lineout, prop Paul James powered to within sight of Gloucester's line and Barry Williams rounded things off.

Two Mercier penalties temporarily eased Gloucester's growing sense of anxiety, yet a Henson strike just before the break made it 15-6 as the visitors found themselves conceding considerable ground without their rested back-row of Peter Buxton, Andy Hazell and James Forrester.

Gloucester had enough problems, but they piled on self-inflicted misery by ending the opening period one man short when wing Mark Foster was sin-binned for cynically preventing the Ospreys taking a quick lineout throw.

Henson punished Foster's blunder, then slotted another penalty deep into injury time to leave Gloucester in deep trouble at 21-6 adrift.

Gloucester had given themselves a mountain to climb and uncharacteristic defensive lapses were never far from the surface as an increasingly confident Ospreys side continued to cut loose.

A crisp handling move saw Parker squeeze over in the corner, then a flash of individual brilliance by the former Wales centre left Gloucester defenders clutching at thin air.

Henson converted both tries, and despite two further Mercier penalties before substitute Richards darted over following a prolonged attack, Gloucester were merely chasing consolation prizes.

Even though they held a 30-point lead, the Ospreys went flat out to increase their six-try tally, but they finished one point short of a half century.