Cardiff Blues won a seven-try Heineken Cup thriller at the Millennium Stadium to take charge of their qualifying group.

The Blues' second successive bonus point win piled pressure on Pool Six rivals Gloucester, whose quarter-final hopes suffered a serious setback.

Blues' record Heineken Cup crowd of just over 27,000 witnessed a free-flowing encounter underpinned by faultless goalkicking from Ben Blair and Olly Barkley.

Teenage wing Leigh Halfpenny scored two incisive tries for the home side, while former Wales captain Gareth Thomas and fly-half Nicky Robinson also crossed to keep Gloucester at a safe distance.

Blair's kicking - 17 points from seven kicks - ultimately made the difference, although Gloucester played their part, with wing Iain Balshaw claiming a try double and full-back Olly Morgan touching down.

Barkley booted three conversions and a penalty, but Gloucester lost both Morgan and fly-half Ryan Lamb to injuries on a day they will want to forget.

Gloucester arrived in the Welsh capital looking to take a grip on their group after beating Biarritz last time out, while the Blues were fresh from a 50-point victory over Italians Calvisano.

It was a final chance for Blues players to impress Wales coach Warren Gatland before he names his autumn Test squad on Tuesday.

Blues back-row forward Andy Powell was among those looking to make a mark after Ospreys flanker Jonathan Thomas underwent groin surgery last week that will rule him out of appointments with South Africa, Canada, New Zealand and Australia next month.

And Powell did not disappoint, delivering a man-of-the-match display that might have been enough to gain Gatland's vote.

Gatland, together with his coaching assistants Shaun Edwards and Rob Howley, looked on as the home side made a dream start, breaching Gloucester's defence from their first attack.

Slick passing created space out wide, but Gloucester were ultimately punished for a missed Morgan tackle on try-scorer Halfpenny as he cut back inside.

Blair converted and then kicked a penalty, leaving Gloucester 10-0 down inside 12 minutes as the Blues' fired-up forwards enjoyed early supremacy.

But Morgan required less than 25 minutes to make amends, rounding off a crisp handling move after Tindall stumbled within sight of Cardiff's line.

Barkley added the extras following an earlier penalty, and although Blair's second succcessful three-pointer kept the Blues ahead, Gloucester were firmly back in contention.

And they went went ahead for the first time, courtesy of a colossal effort by their pack.

Cardiff were pushed off their own scrum ball five metres out, and England number eight Luke Narraway performed the simple task of sending an unmarked Balshaw over.

Barkley booted the touchline conversion, but Gloucester imploded as half-time approached, conceding two long-range tries inside three minutes.

Barkley, who had switched to fly-half after Lamb limped off, flicked out a hopeful midfield ball straight to Halfpenny, and he sprinted 50 metres unopposed for his second touchdown.

Gloucester though, still had enough time to leak another score, with Blair launching a blistering counter-attack from inside his own half, finding centre Jamie Robinson in support before Thomas finished off in style.

Blair kicked both conversions, giving the Blues a 27-17 lead after a breathless first-half of five tries and 44 points.

Gloucester suffered another injury setback four minutes into the second period when Morgan exited the action to be replaced by Willie Walker, but the visitors clearly hadn't learnt their first-half lesson.

Barkley fired out another wildly-optimistic midfield pass that eluded his team-mates and would have sent Blues centre Tom Shanklin clear, had he not nudged the ball forward.

It was a clear let-off, yet Gloucester gathered their composure to craft Balshaw's second try, with first-half replacement Lesley Vainikolo providing the scoring pass.

Typically though, the Blues stormed back downfield, stretching Gloucester's defence, but neither Thomas nor substitute Jamie Roberts could apply the finishing touch.

It proved a temporary reprieve, as the Blues got their act together in a fiercely-fought scrummaging contest to provide the attacking platform for Robinson to cross between the posts.

Blair's sixth successful kick restored a 10-point Blues advantage, before he completed a penalty hat-trick after Gloucester hooker Olivier Azam was sin-binned for killing Cardiff possession.

There was no way back for Gloucester now, and the Blues deservedly took maximum points from an enthralling encounter.