The sides were meeting in a repeat of the 2017 Limerick SHC final.
Heavily billed as the game of the weekend, the clash of Na Piarsaigh and Kilmallock certainly lived up to the hype as the sides played out a brilliant contest.
In the end, it was Na Piarsaigh that reigned supreme, winning by the minimum margin, 1-19 to 1-18 in Doon to take control of the group.
A first half goal from David Dempsey had Nap clear at 1-12 to 0-10 as they looked to build on the defeat of Doon in the first round.
But Kilmallock, who were so impressive against Patrickswell, hit their grove in the third quarter and led by Shane O’Brien, hit the front when the teenager found the net.
Na Piarsaigh, six times champions in the last eleven years, didn’t panic and found the necessary scores to pull two clear, Adrian Breen supplying the insurance score.
And while Kilmallock did get within one, they couldn’t find the equalizer as Na Piarsaigh moved out on their own with four points in the group.
Watch the highlights from the contest below, or watch in full here.
The teams now have an almost month long wait for round three, with three group games to play.