Approaching the four-mile mark of the 2017 Grand National, Blaklion had a commanding lead and looked every bit the winner of the famous race. The problem was the Grand National is 4 5/16 miles. In the last quarter-mile, Blaklion was passed, eventually finishing fourth, 8 3/4 lengths behind winner One For Arthur. On Saturday at Aintree Racecourse, just north of Liverpool, England, a field of 40 will start in the $1.41 million Grand National, one of racing’s true spectacles. The race is run over 30 fences that are larger and more demanding than conventional steeplechase obstacles. Blaklion, a 9-year-old gelding, was one of three 10-1 favorites in future-book betting as of Thursday, along with the Irish invaders Anibale Fly and Total Recall. One For Arthur sustained a tendon injury last fall and has not raced during the 2017-18 steeplechase season. Blaklion, trained by Nigel Twiston-Davies of England, has been pointed to the Grand National since last year’s running. After a game second in the Charlie Hall Chase at Wetherby in early November, Blaklion won the Becher Handicap Chase at 3 1/4 miles over the national fences at Aintree in December. Earlier this year, Blaklion was second in the Grand National Trial Handicap Chase at Haydock Park and underwent an operation three days later to aid his breathing. He has not started since. Aside from One For Arthur and 2017 runner-up Cause of Cause, the remaining top 10 finishers from 2017 are back: Saint Are, who was third, as well as Gas Line Boy, Vieux Lion Rouge, Lord Windermere, Regal Encore, Pleasant Company, and Houblon Des Obeaux, who were fifth through 10th. The Grand National is a handicap. Minella Rocco, who was third in the 2017 Cheltenham Gold Cup, but fell in his last start in the Irish Gold Cup at Leopardstown on Feb. 4, is the 164-pound highweight, and will carry one more pound than Blaklion. Minella Rocco, an 18-1 chance as of Thursday, underwent a wind operation in early February. Irish-trained runners have been popular with early bettors. Anibale Fly, who will carry 161 pounds, was third in this year’s Cheltenham Gold Cup on March 16. Total Recall fell three fences from the finish of the Cheltenham Gold Cup when racing just behind the leaders. Total Recall will carry 158 pounds on Saturday.