"We have a title to defend but it is going to be necessary to take out the match of the year," said Yachvili, the Amlin Man-of-the-Match in the tournament final 11 months ago.
"We can play without pressure, just play our rugby, and keep working hard.
"It is going to be necessary to be very efficient, very good in defence and very good at the rucks as that is their trump card in defence - they succeed in holding the guys standing.
"And then with Jonny Sexton in their side you cannot give them the chances for him to kick the points.
"Leinster are a massive team - they are the Heineken Cup champions - and they were unlucky to be in with Clermont.
"It is a big challenge for us and although we have had a very hard season, our season is not finished because we are in this semi-final and we will do our very best in the match."