Devin Toner has warned that Leinster need their Ireland contingent to slip back into club mode as smoothly as possible if they're to get out of Montpellier with a victory in this Saturday's Heineken Champions Cup.

Leinster were beaten 25-17 by Saracens in September's Covid-19-delayed quarter-final and begin their 2020/2021 mission in France knowing their opening pool game has assumed heightened importance.

The pandemic has resulted in a format change to the competition, with Leinster facing just two other teams in Pool A - Montpellier and Northampton Saints. There are 12 teams overall in the pool, with the top four progressing, so there's little room for error.

With the Ireland players only returning this week after their Autumn Nations Cup exertions, the province must hit the ground running. 

"Of all weeks, it's hugely important that everyone is singing off the same hymn sheet," Toner told RTÉ Sport.

"We've a lot of guys from international camp coming back in. They don't have that much time to prepare but we've had a really good block of games here. We've put some good scores and good wins in. 

"It's up to them to fit into what we've been doing. I know being in international camp it's very attritional, not just physically but mentally.

"To not get a bit of a break after it is very hard for them but it's just something we've got to do. That's the nature of the season I suppose. They will get their breaks when they can but it's a massive weekend for us.

"The way it's structured now... every point is so important."

Montpellier are 11th in the Top 14 table but they have games in hand and come into the GGL Stadium clash on a high having turned over Clermont 21-15 in their own back yard last Friday night.

"We're coming up against a team that's physically big, with a back line that's quick and fast," added Toner.

"I think where they are in the league doesn't really show how they've gone. They're a fantastic team.

"They overcame Clermont at the weekend which is a big feat - in Clermont as well. They seem to be clicking at the right time.

"There's only four games. We need every point we can get and every win we can get.

"We're away in France. It's going to be tough."