Rathdowney-Errill emerged from the championship opener as nine point winners.
The defending Laois hurling champions have suffered an early set-back.
A meeting of Camross and Rathdowney-Errill promised much before the off and delivered more.
Poor playing conditions didn't prevent entertainment flowing with seven goals and 35 points shared between the two sides.
Camross never fully recovered from a slow start, trailing by six at the break, meaning last year's beaten semi-finalists claimed an early scalp on a final scoreline of 4-21 to 3-14.
In the championship's other group, The Harps face Rosenallis at the LOETB in Portlaoise, while tomorrow Portlaoise and Castletown meet at the same venue.
Both games throw in at 7.30pm.
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