Macs Joy is a former winner of the Irish Champion HurdleThe 2005 Champion Hurdle runner-up Harchibald and last year's second Macs Joy will miss this year's race.
Macs Joy has been ruled out of Tuesday's contest with a pulled muscle while the soft ground conditions have led to Harchibald's withdrawal.
The news is the latest blow to Irish hopes for the Cheltenham Festival.
Reigning Gold Cup champion War of Attrition, the 2006 blue riband runner-up Hedgehunter and rising star In Compliance are all absentees.
Harchibald's trainer Noel Meade, who is based in County Meath, said stablemate Jazz Messenger is an unlikely Champion Hurdle runner, and he will instead rely on Grade One novice winner Iktitaf.
"Harchibald won't travel over as the ground is against him and it is going the same way with Jazz Messenger," said Meade.
Jessica Harrington, the County Carlow-based trainer of Macs Joy, said he is likely to reappear at the Punchestown Festival in April.
Macs Joy was a general 9-1 chance for the two-mile contest, with Harchibald rated a 25-1 shot.
Galloping grey Detroit City, trained by Philip Hobbs in Somerset, is favourite for the race, which has been dominated by the Irish in recent years.
Hobbs trained the last England-based winner, Rooster Booster, another grey who won in 2003.
The 2006 champion Brave Inca and Hardy Eustace, winner for the two previous years, head the Irish challenge this time.