Richard Hill believes his Bristol side are "pumped up" to give Heineken Cup opponents Cardiff a chronic case of the blues on Sunday.
Despite losing twice in Pool Three - away to Cardiff Blues and Stade Francais - Bristol can still reach the quarter-finals.
They will probably need a bonus point victory at the Memorial Stadium to have any chance though - and also hope French champions Stade do not collect a five-point maximum from their away clash against Harlequins on Sunday.
Head coach Hill said: "We have still got a mathematical chance of going through, and the players are ready and all pumped up for it.
"We are the outsiders. I think Stade Francais and Cardiff are probably the favourites, but we could surprise everyone at the end, you never know.
"There is a huge incentive for us.
"We will need to concentrate and keep our discipline. We didn't do that at Cardiff (in November) and conceded three late tries.
"Cardiff keep going and going and wear you down. They will keep running the ball at you, and your defence has to be absolutely spot-on for 80 minutes."
Bristol, unbeaten at home in all competitions since mid-September, have called up wing Anthony Elliott after David Lemi flew home to New Zealand because of a family illness.
Changes in the pack see starts for prop Alex Clarke and flanker Alfie To'oala, but a star-studded Blues side will travel in confident mood, having beaten Bristol 34-18 during the opening round of pool fixtures.
Lesley Vainikolo, meanwhile, will return to the Gloucester line-up for Sunday's Pool Two encounter against Ulster at Kingsholm.
The former Bradford Bulls rugby league star has not played since December 29, having headed back to New Zealand following the death of his father.
But Gloucester will field Vainikolo for the Ulster game, which comes just 24 hours before he meets up with England's RBS 6 Nations squad at Twickenham.
Vainikolo said: "I have been fortunate to have received a great deal of support, but I am really happy to be back, be around the boys again and thinking about rugby.
"It is great I have an opportunity this weekend, and I want to go out and repay the faith people have in me.
"There is a job to do on Sunday and we must make sure we achieve it."
With the juggernaut wing absent, Gloucester lost their last two games - against Guinness Premiership opponents Bath and Heineken Cup rivals the Ospreys.
Victory on Sunday, though, would see the Premiership leaders secure a home quarter-final.
Vainikolo is among six changes from the side thumped 32-15 by the Ospreys in Swansea last weekend, as head coach Dean Ryan also hands starts to fly-half Chris Paterson, scrum-half Rory Lawson, prop Nick Wood, hooker Olivier Azam and flanker Alasdair Strokosch.
Peter Buxton, meanwhile, moves from back-row to second-row duties as replacement for broken-arm victim Alex Brown.
The Ospreys are poised to claim one of two best runners-up spots, although they must beat French hosts Bourgoin on Sunday or face elimination.
Ospreys head coach Lyn Jones said: "It is really quite simple - we have to go there and win.
"It would be fantastic for Welsh rugby if Cardiff Blues and ourselves could both qualify.
"It is all there to play for, and that is the beauty of the Heineken Cup - it is right on a knife-edge from start to finish."
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