The 35-year-old joined Ronan O’Gara (110), Gordon D’Arcy (104), John Hayes (101) and Peter Stringer (101) in the elite group of players to have achieved a century of games in EPCR’s leading tournament when he came off the bench in Leinster’s 49-14 win at Gloucester Rugby on Saturday.

At the other end of the experience spectrum, several players made their EPCR debuts in the victory, which secured Pool A leaders Leinster’s place in the Round of 16.

“We’ve a number of players who hit milestones there,” Cullen pointed out. “I see Mikey Milne with his dad out there, European debut, Brian Deeny and Liam Turner the same.

“Cian making his 100th appearance in the competition is an amazing achievement. I remember Cian when I first met him, you were never too sure what to make of him, how could this guy survive as a professional?

“How he’s progressed in terms of his own diligence and professionalism, he’s phenomenal.”

Despite recording a third straight bonus-point win, one cause for concern for Leinster was the concession of two penalty tries at Kingsholm Stadium amid illegally collapsed mauls close to their own line.

Cullen says it is an area Leinster are working on as their mission to avenge their gut-wrenching defeat to Stade Rochelais in last year’s final continues.

“We want to go after teams in that facet of the game,” he explained. “The two tries, [the question is more] why are we ending up in that situation when we have to defend half a dozen lineout mauls from five metres out?

“Obviously we gave away two penalty tries there but Gloucester are a well-drilled team.

“Most coaches would be looking at what they do, George [Skivington] has done a really good job there and you’re seeing it week on week where they’re scoring tries from lineout mauls.

“I’ll have a look at it back in a bit more detail, the lads will have a look at it for sure, but there are other facets of the game that we can definitely improve on but overall, I think the mindset has been pretty good.”

Leinster’s pool stage campaign is wrapped up next Saturday as they welcome Racing 92 to the Aviva Stadium, with top seeding – and subsequent home advantage in the knockout stage - the target for the Dublin side.

“We’ve got Racing in the Aviva next week,” Cullen added. “It’s exciting for our players to be in front of friends and family.

“Racing are tricky opponents for us, they’ve plenty of quality in their squad, in front of close to a full house.”

Leinster Rugby head coach Leo Cullen heaped praise on prop Cian Healy after he became only the fifth player to make 100 appearances in the Heineken Champions Cup.