Nicky Henderson's youngster had already triumphed over Colin Tizzard's chaser at Cheltenham and Sandown but he only asserted his authority in the final strides this time.
With Henderson looking for a decisive answer for Captain Conan's Cheltenham target, his charge looked in trouble some way out as Third Intention (11-1) forged clear.
However, Tizzard's runner found the Sandown hill too much and Barry Geraghty seized the opportunity to galvanise the 1-2 favourite and win by a neck. "It was definitely harder work than we thought," Geraghty said. "He jumped nicely, but I knew from the water jump it was going to be hard work.
"Nicky has an indoor school which has kept them on the go, but I'd say he just lacked a bit of race fitness."
Paddy Power pushed Captain Conan out to 6-1 from 4-1 for the Jewson at Cheltenham.
Another trainer dreaming of Prestbury Park was Nick Gifford after On Trend stayed on gamely to win the Betfred Masters Handicap Chase.
Four of the winner's rivals hold Grand National entries but it was On Trend, returned at 7-1, who showed most stamina under Tom Cannon to master Viking Blond (also 7-1) by eight lengths.
In-form trainer Venetia Williams kept up her good run with a double. Kapga De Cerisy, the 11-8 favourite, held off Itoldyou (5-1) to win the Betfred "Double Delight" Novices' Handicap Chase and 6-5 favourite Shangani was victorious by seven lengths in the Betfred "Hat Trick Heaven" Handicap, with Aidan Coleman in the saddle on both.
The complexion of a competitive race changed in the straight with several horses holding chances, including Tanerko Emery, owned by Ffos Las chairman Dai Walters, after favourite Oscara Dara weakened tamely.
However, Tanerko Emery (4-1) had to settle for third as Peckhamecho (25-1) made his bid for glory, only for Medinas to sweep past and win by a length and a quarter, with Tanerko Emery a neck further behind.
"He travelled and jumped well," Hutchinson said. "He has come back a fresher horse after a break and did the job."
Speaking from Sandown, King said: "I did say to Choc [Thornton] yesterday 'which one do you want to ride?', There's nothing between [the two horses] in the ratings. But we both agreed he should be on Balder Succes. He was disappointing. I don't think he stayed."