Blaklion will miss next week's Randox Health Grand National at Aintree Racecourse following an injury setback.
The 10-year-old, who finished fourth in the Aintree marathon in 2017 and won the Becher Chase later that year, was due to make his debut for trainer Phil Kirby on Merseyside next Saturday.
He was bought by Darren and Annaley Yates out of Nigel Twiston-Davies' yard in February and was on course to line-up in the world's greatest steeplechase for a third time.
Despite giving an upbeat bulletin on Thursday of Blaklion's well-being trainer Kirby has now taken him out of the Aintree showpiece following a back problem.
Kirby said: "He's got a back joint problem and he won't be running next week.
"I'm disappointed, the owners really wanted to have a National runner and we've done everything we can to get him there in one piece.
"It's not something that will stop him forever, but most likely for this season."
