Lying third in Pool 3, Connacht take on current English Premiership leaders Saracens on Saturday, although even a bonus-point victory may not be enough to put them through.
A win could nevertheless could also see them progress through to the knock out stages of the European Challenge Cup.
And having stunned Toulouse in France last month, Lam knows a third away win in the competition this season is a real possibility if they all pull together.
"It's quite a massive game for us. We have a chance, we have put ourselves in a position in the way the games have gone (last) weekend," Lam told the Irish Independent.
"If we win we'll definitely be in Europe, it's just a case of what competition. So for us to achieve that we have to focus on ourselves, have a clear game plan.
"Going to Toulouse to win, we did our work, figured out a way to beat them. Then collectively as a group the boys worked on that process and stayed together. That's the only way we are going to win.
"There is no chance for us if we go individuals against individuals. But collectively as a group we have got a chance."
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