The All-English clash at the Twickenham Stoop will be keenly contested with both sides harbouring genuine ambitions of qualification.

Harlequins drew 13-13 with Cardiff Blues on their last outing but gained a psychological edge over their pool 3 opponents with a 24-18 win in their Guinness Premiership meeting in London two months ago.

Bristol produced the shock of the last round after toppling tournament favourites Stade Francais 17-0 at the Memorial Ground and in the process have thrown the group wide open.

But the West Country club, who welcome back hooker Mark Regan from Barbarians duty, have only ever won once on the road in the Heineken Cup back in March 2003 with a 30-22 success at AS Montferrand.