But victory over Pool Four rivals Castres at Stade Pierre-Antoine on Friday would confirm all-important home advantage when the tournament resumes later this season.

"It's about getting a home quarter-final - that is certainly the big driver for us," Leinster coach Lancaster told leinsterrugby.ie.

"I think French teams are different away from home than they are at home.

"I think we beat Castres at the RDS (in Dublin), and then they won their next two games. They are a tough team at home and a very proud team.

"We can't get complacent or underestimate the challenge that is coming our way."

Leinster confirmed top spot in the group by thumping Montpellier in eight-try fashion last Friday, capitalising brilliantly after there was an early red card for opposition fly-half Frans Steyn.

And Lancaster added: "I felt we put a lot of pieces of the jigsaw together at the RDS on Friday night, and I think now it's the challenge to do it away from home.

"We've done it intermittently away from home, but we've never had a consistent 80-minute performance. That is what we are driving for this Friday.

"Castres will be disappointed with having lost to Northampton (last weekend). They are a different team to Montpellier. They play a lot more unstructured rugby, good on counter-attack.

"I think it will be an open game - we need to be ready."

Fly-half Johnny Sexton, despite being on the receiving end of Steyn's dangerous challenge that resulted in the South African being sent off, starts in a Leinster side showing three changes, with prop Cian Healy, hooker Richardt Strauss and lock Ross Molony all featuring.

"I think we played pretty well before Montpellier lost (Steyn) with the red card," Lancaster said.

"I think if they had have kept 15 players on the field, they would still have struggled to deal with us. I thought it was a very good performance from the first minute to the 80th."

Montpellier, meanwhile, could still reach the quarter-finals, but they effectively need a bonus-point victory over visitors Northampton on Friday, and then hope other results work in their favour.

"We have to play for the jersey, because we were ashamed last week," Montpellier wing Nemani Nadolo said.

"We did not give a true image of what our club is all about. We must redeem ourselves on Friday. There is pride in this team."

Northampton show nine changes from the side that beat Castres last Saturday, with scrum-half Lee Dickson captaining a team that also features Wales wing George North, JJ Hanrahan at fly-half and Teimana Harrison in the number-eight role.

In the European Challenge Cup on Friday, Edinburgh will secure a quarter-final berth if they beat Romanian side Timisoara Saracens, while a five-point maximum would guarantee a home draw.