The Nigel Twiston-Davies-trained runner finished fourth after being sent off the 8-1 favourite for last year's renewal of the Aintree spectacular and after being given 11st 6lb for this year's race, he is the general 10-1 market-leader ahead of an intended appearance in the Betfred Grand National Trial at Haydock on Saturday.
William Hill spokesman Rupert Adams said: "Blaklion is 10-1 favourite for the Grand National and is set to go off as the worst result for the bookies in decades."
Betway trimmed Willie Mullins' Total Recall to 14-1 from 16-1. The nine-year-old has won the Munster National, the Ladbrokes Trophy and a handicap hurdle at Leopardstown since joining Mullins from the now-retired Sandra Hughes and has been allotted 11st 1lb for the world's most famous steeplechase.
Betway's Alan Alger said: "Total Recall has been impressive on all three of his starts since moving the Mullins yard and is only headed in the market by Blaklion at 10-1."
The same firm trimmed Nicky Henderson Gold Present (11st) to 20-1 from 25-1, but pushed out Outlander to 40-1 from 33-1 after he was given 11st 8lb.
Five of the previous 10 winners of the the Grand National carried over 10st 12lb and the leading online bookmaker offer 11-8 for it to happen again in 2018.
It is 15-8 for a horse to carry 10st 7lb or less to victory, while 10st 8lb-10st 11lb rates as a 9-4 chance with the Grand National Festival's official betting partner.
Paddy Power offer just 2-5 that the winner is trained in the United Kingdom, an Irish-trained winner is rated a 7-4 chance and punters are offered 11-8 that the entire 40-runner field jumps the first fence.
Total Recall is one of 10 entries for Mullins and he is a 12-1 shot to saddle his second National winner following the popular success of Hedgehunter in 2005.
Following the publication of the weights, Sky Bet are offering the non-runner no bet concession and are paying five places on all each-way bets.
Blaklion is 10-1 in the Sky Bet book, Total Recall is 12-1 and Definitly Red, who is top-weight with 11st 10lb, is third in at 16-1.
Sky Bet Racing PR manager Michael Shinners said: "The release of the Grand National weights is always eagerly anticipated and now Sky Bet punters can place their bets on the great race knowing they will get their money back if their horse doesn't line up.
"As ever it looks a fiercely competitive renewal and while Blaklion and Total Recall have been popular so far, there will be plenty more movers between now and the tapes going up at Aintree."
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