Warren Greatrex's Missed Approach has been ruled out of the Randox Health Grand National.
A winner at the Cheltenham Festival last season, Missed Approach had been targeted at Aintree all this term but will miss the big race because of injury.
Greatrex said: "Unfortunately, Missed Approach was found to be lame a couple of days ago.
"We've had a look at it - and while it's nothing serious, I'm not going to be able to get him back this season.
"He should make a full recovery, and hopefully next season we can go along the same lines."
All had previously gone well throughout the campaign, and Greatrex added: "It's a huge blow to us - because last year, after winning the Kim Muir, the plan was to have a go at the National this season.
"We ticked off another box when we went to the Becher Chase, because he took to those fences, and we were happy with him and the weight he had for the race."