Isa Nacewa admits Leinster and Clermont Auvergne know each other so well their crunch Heineken Cup meeting on today is almost a derby fixture.

Two-time defending European champions Leinster face the Top 14 giants at Stade Marcel Michelin, where the French club have not lost in over three years.

Both sides are unbeaten thus far in Pool Five, and their meetings this weekend and next will go a long way to deciding who will win the group and guarantee a quarter-final berth.

This will be the fourth consecutive season in which Leinster and Clermont have clashed in the Heineken Cup, but winger Nacewa says familiarity does not make life any easier for the defending champions against a team including the likes of Morgan Parra, Aurelien Rougerie and Julien Bonnaire.

Nacewa told Leinster TV: "They had Parra, Rougerie and all their big names playing last week, as well as a big pack with some big names so they have prepared well to play us.

"This fixture has turned into a bit of a derby over the last few years. I have said they are not a team you want to come up with in the group stages and we have had them twice in the last three years.

"They have an unbelievable squad and every player is a good one. But we have to be confident going there, they have not lost there in going on for 50 home games so we have to focus on how we perform."

"They have an unbelievable squad and every player is a good one" - Isa Nacewa

The game will also pit Clermont coach Vern Cotter against former cohort Joe Schmidt.

The pair worked together in France before Schmidt elected to make the move to Leinster, and Cotter knows how important these fixtures are if his side are to progress.

"Qualifying from the pool will depend on this double header," said Cotter.

"They, as we have done, have long marked this date in the calendar.

"My players are very excited, focused and motivated by the idea of playing this match."