Gloucester are banking on "streetwise and experienced" Scotland star Chris Paterson to steer them towards a Heineken Cup quarter-final place on Sunday.
Paterson takes over from rested England fly-half prospect Ryan Lamb against Kingsholm visitors Ulster.
And having waited patiently for his chance - he has not started a game since before Christmas - the result could prove spectacular.
Paterson displayed trademark quality during substitute appearances against Bath and the Ospreys in recent weeks, and the Heineken Cup stage now awaits.
Gloucester head coach Dean Ryan said: "I think it shows the strength of our squad that we are able to rotate two players of the quality of Ryan and Chris.
"Chris is a guy of proven international quality and has a wonderful record. We are hugely fortunate to have him for a game of this calibre and in these conditions. He is streetwise and experienced, and they are crucial qualities."
Paterson is among several changes to Gloucester's line-up after Pool Two rivals the Ospreys grounded them 32-15 in Swansea last Saturday.
The most notable is wing Lesley Vainikolo's return, having been absent throughout January following the death of his father in New Zealand.
Scrum-half Rory Lawson, hooker Olivier Azam and flanker Alasdair Strokosch also start as Gloucester target a victory that will guarantee a home quarter-final tie.
The Ospreys need victory over French hosts Bourgoin on Sunday to qualify as one of two best runners-up, and they are unchanged following their Gloucester demolition job.
"We are starting to hit our straps at the right time," said the Ospreys' former All Blacks flanker Marty Holah. "We are right on the edge of breaking through to another level for the region."
The Ospreys and Cardiff Blues can make it two quarter-final representatives for Wales - that has not happened since 2001 - with the Blues guaranteed to top Pool Three if they beat Bristol on Sunday.
Blues' Wales centre Tom Shanklin said: "We have not qualified for the quarter-finals since I've been here and while we've had opportunities to qualify, none of those chances were quite as big or good as this one. It really would be a great step forward for us if we can go through to the quarter-finals."
Despite losing twice in Pool Three - away to Cardiff and Stade Francais - Bristol can still reach the last-eight. 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.
Bristol head coach Richard 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.
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