The two sides came into the game in fine form with Leinster unbeaten in the United Rugby Championship and off the back of an away victory in Bristol to start their European campaign.
Clermont, meanwhile, had enjoyed a bonus-point win against Benetton seven days prior and sat third in the Top 14.
Both rolled the dice in the selection of inside centres in new positions.
Short-term signing Barrett made his first Leinster start as a fullback, a position familiar to the 67-times capped All Black from earlier in his career but he had not worn the 15 jersey in two years.
For Clermont, Australian Irae Simone had never started a professional game at fly-half but was wearing 10 in Dublin.
The newcomer to the jersey had a hand in the game’s opening try.
It was his grubber through that came off the boot of Max Deegan and was gathered Pierre Fouyssac. After the centre was hauled down short of the line, Raka crashed over from close range.
Across the opening quarter, a frustrated Leinster saw line-outs lost and passes both drift forward and go to ground.
It was not until the 21st minute when things really clicked, Garry Ringrose the beneficiary as he went over one pass after Deegan produced a brilliant offload out the back for Prendergast.
Clermont were foiled in their attempts to strike back immediately when a thrilling move ended when Alex Newsome lost the ball charging for the line and Leinster went straight up the other end to score.
This time, it was from a clever tap and go penalty five metres out with Barrett’s second try in as many appearances for Leinster popular among the Dublin crowd.
Despite taking some time to move through the gears, Leinster would likely have felt that with a stronger line-out, they could have been further ahead at the turn.
