Two of his opponents in that game, and fellow debutants, had a combined age that was less than that of Mulhearne.
Mulhearne was called into the team after Aaron Beresford sustained an injury.
Mulhearne had first been part of the Waterford senior team as a 17-year-old schoolboy, but never played.
The lowest ranked counties to play in the quarter-finals are Limerick and Waterford of Division 4.
The lowest ranked counties to play in the semi-finals are and Limerick of Division 3.