The three best-placed pool runners-up also progress to the last eight, so a victory plus reliance on matters elsewhere on the continent could prove enough.
And though Enisei have lost both of their previous European away matches this term, shipping 88 points in the process, Lam will not entertain any complacency.
"We know we will need a clinical and focussed performance that ensures we take our chances and scores," he said.
"Enisei will be coming here with confidence following their defeats of both Brive and Newcastle in our pool.
"They are a big, physical side and can do some damage if they are given a chance. But it's up to us to take control of this game from the start."
Lam has made six changes to his side that took on Brive last weekend, which includes the return of influential Ireland centre Robbie Henshaw.
"It's great to have some guys back from injury for what is a crucial game for us in terms of our European ambitions," Lam added.
"We are really excited to be back at the Sportsground and we are determined to give our loyal supporters something to cheer about."
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