Manchester United have withdrawn from this year's Milk Cup youth football event and the club's defender Paddy McNair has also pulled out of Tuesday's scheduled competition draw.
The competition's organisers says that they have been left "shocked and disappointed" by the club's move.
A United statement said that they had taken the decision after assessing the club's "pre-season training needs".
McNair's absence has led to the postponement of Tuesday's draw.
"We know Paddy was keenly anticipating his role with us on Tuesday but permission for his participation was cancelled," said Milk Cup tournament chairman Victor Leonard.
"We had invested considerable time and money on the technical aspect of our visual presentation for the draw itself so that needs to be revamped.
"We are also in the process of finalising another team to replace United.
"Thankfully, we are always over-subscribed in all sections of the event but it is a matter of ensuring a replacement and putting the necessary wheels in motion to compete at short notice with the event just two months away."
The Old Trafford outfit have been supporters of the international youth tournament for 25 years with former boss Sir Alex Ferguson an active advocate of the Northern Ireland event.
In a brief statement United said: "After a thorough assessment of the pre-season training needs of the first team and a detailed assessment of the medical impact of that plan on the reserves, Manchester United has decided not to enter a team in the Dale Farm Milk Cup."
The competition's six-time Premier champions have a massive following in Northern Ireland and tournament chairman Leonard said the club's decision had come as a "shock".
"This will come as a huge blow to the legions of United supporters in the province who back the club over the week of our event," added Leonard.
"We had written confirmation from them that they would be competing and the fact they have gone back on their word is extremely disappointing."
The competition will take place in North West venues from 26-31 July.