Leinster winger Jordan Larmour says they are bracing themselves for a battle at Toulouse this Sunday.
The holders began their defence of the Heineken Champions Cup with an eight try 52-3 rout of Wasps at the RDS last weekend.
But Larmour is not expecting things to be as straightforward in France.
"It's always a tough place to go, I got a bit of a taste of it last year against Montpellier," said Larmour.
"Just seeing how they feed off the crowd and the noise they bring.
"Even when the 10s are taking kicks, they are screaming and shouting.
"So it's a tough place to go but we're looking forward to the challenge."
Larmour was among those to score a try in last week's Champions Cup opener helping Leinster off to a perfect start as they seek to retain the cup.
Following the emphatic win at the weekend, head coach Leo Cullen was keen to lose sight of the challenges ahead.
"We just need to be careful that we're not getting too far ahead of ourselves. We've played one game and no one else has played yet in Europe. There's a lot of very good teams in Europe at the moment," he said.
What a way to start our European title defence! 💪🏆October 16, 2018
"Sometimes in Europe, you only need to be a little bit off and you come unstuck. Sometimes then the score can get out of control.
"We know that ourselves, because we got beaten by Wasps 51-10 in the Ricoh a number of years ago and we got pretty heavily beaten here as well. It can be a little bit misleading at times."