Irish Premiership clubs Cliftonville and Linfield have decided not to enter the 2014 Setanta Cup competition.
The development is bound to raise questions about whether the All-Ireland competition will take place next year.
Linfield, the inaugural winners of the tournament in 2005, said reduced prize money and the scheduling of the matches led to their decision.
Current Premiership champions Cliftonville said their busy fixture list had prompted their withdrawal.
"Our heavy schedule began with the Champions League in July, and we have decided not to take up the invitation this season," a statement read.
"We enjoyed being part or the tournament in previous years and do not rule out participation in the future."
Linfield said: "With a much reduced prize fund available to competing clubs, and also taking into account the considerable difficulties faced by our supporters travelling to attend games, the Board of Directors has taken the decision not to enter the competition."
The loss of two of the top teams from Northern Ireland's top flight, will lead to speculation about the viability of the cross-border competition.
In the eight years of the Setanta Cup, Linfield and Crusaders are the only Irish League clubs to have won the trophy.
In the 2013 final, Shamrock Rovers beat Drogheda United 7-1.