Davy Russell will miss the 2021 Cheltenham Festival.
The top jockey, who was set to ride odds on favourite Envoi Allen in the Marsh Novices' Chase, has not recovered in time from injury.
Russell has been sidelined since November, when he broke his neck in a fall at Limerick.
And although the 41-year-old has made excellent progress from the accident in the Munster National, he will not be ready for the big March fixture.
"I met with my surgeon earlier today and, although he is delighted with the progress I have made, he feels I am not quite where I should be in order to ride at Cheltenham next month," Russell said in a statement.
"It is frustrating as I feel I have made giant strides in recent weeks on the road to recovery.
"However, after talking things through with Gordon (Elliott), we both feel it is sensible for me to follow advice and miss Cheltenham as it is only weeks away.
"To ride the horses of the calibre of Envoi Allen you have to be 100 per cent fit and I would be doing the team a disservice to ride when I'm not ready.
"Obviously, it is hugely disappointing, but it is important to make the call early.
"I will continue to work hard on my recovery and look forward to getting back in the saddle the following month.
"I remain so grateful for all the extraordinary medical attention I have received and thank you for all your lovely messages of support."
Unbeaten novice chaser Envoi Allen, 4-5f with Paddy Power for his Festival target on day three, has been ridden by Jack Kennedy this season.
The partnership is expected to continue while Russell is out of action.
He was also due to team up with Elliott in other races, the meeting's leading trainer in 2017 and 2018.
