If Leinster can gain the upper hand in the physical stakes, Stade's interest in the contest will dry up. If Leinster give them nothing to play for, especially at scrum time, the French team will go looking for the gate early on. Win the physical battle and Leinster win the match.
2 Be disciplined
They cannot afford to give Stade penalties. If they minimise Stade's opportunities to keep the scoreboard ticking over, they'll break their will. Leinster must not give away unnecessary penalties, especially at the breakdown.
3 Trust in themselves
Leinster aren't at their strongest, especially with Brian O'Driscoll missing. But they have enough talent in their side to win the game. They need to trust in the abilities of the likes of Ian Madigan and Fergus McFadden to out-think and out-perform their opposition.