Holders Gloucester will remain firmly on course for a successful European Challenge Cup defence if they collect just two points from Saturday's Kingsholm appointment with La Rochelle.
The runaway Pool Four leaders can guarantee quarter-final status by beating La Rochelle, drawing with them or picking up two losing bonus points, as second-placed Zebre - who visit Worcester on Saturday - would then be unable to catch them.
"If we win this game, we will win our pool and that will get us into the last-eight," Gloucester head coach Laurie Fisher said.
"We would like to be one of the top four seeds, working towards a home quarter-final.
"But we need to get this weekend out of the way first against what will be a challenging La Rochelle side that will come to Kingsholm with not a lot to gain, but nothing to lose.
"A French side playing with freedom, given the size of their players and their off-load game, can be dangerous."
And Gloucester rugby director David Humphreys added: "One of the goals we set ourselves at the start of the season was to become the first team to retain the Challenge Cup. We want to ensure that come the end of the pool stages we have a home quarter-final at Kingsholm."
Scotland captain Greig Laidlaw leads Gloucester into battle this weekend, with Humphreys making several changes from the side beaten by Aviva Premiership rivals Exeter last Saturday.
Backs Mark Atkinson, Billy Burns and David Halaifonua all start, while the only two forwards retained from six days ago are Nicky Thomas and Tom Savage.
London Irish tackle Madejski Stadium visitors Grenoble on Saturday, knowing victory would see them overhaul the current Pool Five leaders, but also aware that third-placed Edinburgh remain firmly in the quarter-final mix.
"We had a good result last weekend (against Newcastle)," Irish head coach Tom Coventry said. "We need to be winning regularly, and it certainly does not do any harm if you can get those wins in front of your home crowd.
"I would like to think the win at the weekend can boost confidence. Grenoble have been playing well and they will come fully-loaded after a week off."
The qualification picture is similarly congested in Pool One, with just two points separating top three teams Connacht, Newcastle and Brive.
And that situation cranks up the importance of Newcastle's clash against Russian side Enisei-STM in Sochi on Saturday, where victory for Dean Richards' team would strengthen their quarter-final hopes.
Richards has handed first starts to scrum-half Jamie Booth and number eight Callum Chick, while centre Adam Powell lines up alongside Juan Pablo Socino in midfield after recovering from illness.
Source: PA
