Northampton crushed Cardiff at the Arms Park to set up a potentially decisive clash against French champions Biarritz next month.

Saints, roared on by around 1,000 travelling fans, went top of their qualifying group without having to stretch themselves.

And with Biarritz also standing on three wins from four starts, the stage is set for a Franklin's Gardens showdown.

Northampton, European champions in 2000, were effectively home and dry after just 10 minutes when tries from prop Tom Smith and flanker Andrew Blowers helped establish a formidable 17-0 lead.

Match details

Cardiff (0) 0 Northampton (24) 31 Tries: Cohen, Smith, Blowers, Budgen Cons: Grayson (4) Pens: Grayson Att: 4,700

A cracking Ben Cohen score - he expertly gathered Paul Grayson's cross-kick and cut inside the Cardiff defence to touch down - helped Saints go even further ahead before the break.

And substitute prop Chris Budgen compounded Cardiff's misery on 57 minutes when he powered over from close range.

Fly-half Grayson converted all four tries and kicked a penalty as Cardiff, already eliminated following three successive defeats, suffered their heaviest home loss in Europe.

Only Harlequins and Biarritz had beaten Cardiff previously in Heineken Cup combat at the Arms Park.

But by the time Saints had finished, Cardiff were left contemplating their second-heaviest defeat - home or away - in Europe.

Iestyn Harris is engulfed by the Saints defence

Northampton, having defeated Cardiff 25-11 on home soil eight days ago, blasted out of the starting blocks in blistering fashion.

It took them less than two minutes to open their account when Grayson slotted a short-range penalty when Cardiff strayed offside, and worse was to follow for the Blue and Blacks.

Concerted pressure near the Cardiff line on six minutes resulted in Scottish international Smith touching down for the try that Grayson converted.

Smith had been dropped for the first game between these clubs last weekend as a disciplinary measure after he missed a team meeting, but he responded with a man-of-the-match performance.

Cardiff could not break out from their own half, and they conceded another try just four minutes later.

John Leslie and Chris Hyndman combined cleverly in midfield, and New Zealander Blowers sprinted away for a score which Grayson also improved.

Tom Smith powers his was over the tryline

Cardiff temporarily stemmed the flow of points, but they were undone again five minutes before the break when England star Cohen displayed all his pace and power after Grayson showed superb vision to find him through a neat kick.

Grayson's conversion made it 24-0 at half-time, even though Saints had lock Rob Hunter sin-binned for off-side at a maul, the damage has been done.

Northampton coach Wayne Smith could afford to start using his substitutes early in the second period, and Budgen's score midway through the second period proved the only real highlights.

Tempers became frayed, especially on the Cardiff side, as the game entered its closing stages, and lock Heino Senekal was yellow-carded by French referee Joel Jutge.

Cardiff: Donavan van Vuuren; Anthony Sullivan, Jamie Robinson, Nick Robinson, Craig Morgan; Iestyn Harris, Richard Smith; Peter Rogers, Lewis Collins, David Young, Heino Senekal, Adam Jones, Rob Appleyard, Emyr Lewis, Robin Sowden-Taylor.
Reps: Tim Payne, Darren Fenton, Tate, Dan Baugh, Ryan Powell, Dean Dewdney, Matt Allen.

Northampton: Nick Beal; Oriol Ripol, Chris Hyndman, John Lesile (capt), Ben Cohen; Paul Grayson, Ian Vass; Tom Smith, Steve Thompson, Robbie Morris, Steve Williams, Rob Hunter, Andrew Blowers, Budge Pountney, Mark Soden.
Reps: Dan Richmond, Chris Budgen, Jon Phillips, Simon Hepher, Johnny Howard, James Brooks, Jon Sleightholme.

Ref: Joel Jutge (France).