Cardiff Blues cruised into the Heineken Cup quarter-finals after ending Bristol's four-month unbeaten home record with a 17-0 win.

Despite stamina-sapping conditions at the Memorial Stadium, Cardiff's superior energy reserves helped them secure a victory that clinched top spot in Pool Three.

It clinched a last-eight appointment with French giants Toulouse, while Bristol bowed out, beaten for the first time on home soil since Guinness Premiership champions Leicester toppled them on September 16.

Cardiff went about their business in meticulous fashion, refusing to be knocked out of their stride by clinging mud and persistent heavy rain.

First-half tries in rapid succession from flanker Maama Molitika and centre Gareth Thomas - both converted by full-back Ben Blair, who also kicked a penalty - kept Bristol at a safe distance.

The home side were never seriously in contention, despite a couple of threatening runs by wing prospect Tom Arscott, as Cardiff joined fellow quarter-finalists Saracens, London Irish, Gloucester, Toulouse, Munster, Perpignan and the Ospreys.

The Blues knew victory would be enough to secure a quarter-final place, and they arrived in the west country buoyed by New Zealand imports Blair and Xavier Rush both agreeing new three-year contracts.

Bristol were without wing David Lemi, who flew home to New Zealand last week because of a family illness, so Anthony Elliott started, while changes up front saw call-ups for prop Alex Clarke and flanker Alfie To'oala.

Elliott was quickly involved in the action, carving through an outside attacking channel and sending full-back Luke Arscott diving over Cardiff's line.

Referee Alain Rolland though, on advice from his touch judge, called play back for an Elliott forward pass, and Bristol's hopes of an early try were dashed.

The Blues suffered an identical fate 12 minutes later, being denied when centre Tom Shanklin's inside pass to wing Jamie Roberts drifted forward and prevented a thrilling 50-metre move being rounded off in style.

Cardiff were at it again eight minutes later, this time when Wales flanker Martyn Williams dived over in the corner, but Bristol skipper Matt Salter's tackle nudged him into touch and a gripping contest remained scoreless.

Cardiff were not to be denied and their territorial dominance was finally rewarded with two converted tries in four minutes immediately before half-time.

Molitika claimed the first, powering over in tandem with his back-row colleagues Williams and Rush.

As with Williams' disallowed effort, Rolland again referred it to the video official, but this time he ruled in Cardiff's favour, with Blair adding the extras.

Bristol, who had not threatened following their early attacking promise, were undone again in first-half stoppage time.

Cardiff drove a lineout relentlessly forward, and when Bristol struggled to regroup quickly enough in defence, former Wales captain Thomas' looping run saw him cross.

Blair again converted, taking Cardiff 14 points clear and leaving Bristol with little hope of hauling themselves back into the game.

The home side suffered an injury blow within four minutes of the restart when centre Neil Brew limped off to be replaced by Sam Cox, and Cardiff quickly extended their lead through a Blair penalty.

Bristol continued to give their all in the forward exchanges, yet they lacked the midfield class and craft of Cardiff centres Thomas and Shanklin, whose partnership proved a constant threat.

Cardiff's victory means Wales will have two Heineken Cup quarter-finalists for the first time since 2001.

Had the Blues claimed another converted try though, they would have finished above Toulouse as fourth seeds and booked a home draw against them, but they now face a daunting trip to southern France in early April where the three-time European champions await them.