Tidal Bay has been allotted top weight of 11st 10lb in the John Smith's Grand National at Aintree on 6 April.
The Paul Nicholls-trained 12-year-old has been in tremendous form this season, finishing second in the Hennessy at Newbury to Gold Cup favourite Bobs Worth and then winning the Lexus Chase at Leopardstown.
He has an official British Horseracing Authority mark of 171 but has been rated on 162 by official handicapper Phil Smith, who is allowed to use his discretion in framing the National weights.
A strong Irish-trained entry of 31 features the Ted Walsh-trained pair of Seabass (11st 2lb) and Colbert Station (10st 11lb).
Seabass carried 4lb less when third 12 months ago, and Walsh, speaking before seeing the full list of weights, said: "I don't know how Seabass can get over 11st this year if Tidal Bay is rated 171 and my horse is rated 154.
"Whatever Phil Smith does, he does - it is immaterial to me and I can't change it. You don't have to be a great mathematician to subtract 54 from 71."
Seabass returned to the racecourse for the first time since his gallant Aintree effort to run a staying-on second over two miles in a hurdle race at Fairyhouse last week.
Walsh said: "Seabass will run somewhere in the next three weeks to a month. There is just over seven weeks to Liverpool so I would like to get a run into him. The Bobbyjo Chase at Naas and the Racing Plus Chase at Kempton are possible targets."
As well as Tidal Bay, Paul Nicholls, who won the National for the first time last year when the now-retired Neptune Collonges also has Becher Chase runner-up Join Together (10st 12lb), and a pair part-owned by Sir Alex Ferguson in What A Friend (11st 5lb) and Harry The Viking (10st 2lb).
Tidal Bay is owned by Andrea and Graham Wylie, who also have leading contenders On His Own (10st 10lb) and Prince De Beauchene (11st 3lb), both of whom are trained by Willie Mullins in Ireland.
Jonjo O'Neill's Sunnyhillboy, runner-up last year, has 11st this year compared to 10st 5lb in 2012, while the Donald McCain-trained Ballabriggs, successful in 2011, is another on 11st, the same weight as he carried to victory under Jason Maguire.
McCain said: "That weight is fine for Ballabriggs and it will be grand if the top horse (Tidal Bay) runs because then we will have a lovely racing weight.
"He has come out of his race at Warwick OK. He will go to Kelso for the Premier Chase, as he has done for the past two years, and then on to Aintree."