Nick Gifford hopes Didtheyleaveuoutto can prove him wrong by handling the ground in the Weatherbys Champion Bumper at Cheltenham on Wednesday.
The JP McManus-owned five-year-old looked a potential star when following up his debut victory at Lingfield in a Listed event at Ascot in December.
Gifford said: "He is in great form, but he has never been on this sort of ground before so it is a massive unknown for us.
"He has a great action and we will find out on Wednesday if he goes on it. If he does handle it, he will be an even more exciting horse going forward.
"Barry (Geraghty, owner's retained rider) has hopped on to the other one (Rhinestone) as he rode our one at Ascot and he obviously feels the other horse has got a better chance on the ground.
"Since Straw Bear (runner-up in the 2006 Supreme) we've not had a horse show this much so early in their career. It is very exciting, win, lose or draw, as we have a very exciting horse for the future."
Anthony Honeyball feels dual Listed winner Acey Milan will have plenty in his favour in his quest to complete a four-timer.
He said: "He's done all his winning on soft ground. He's won on the course and has won two Listed events - one against older horses and one against younger horses.
"He also gets a lumpy weight allowance for being a four-year-old. He's getting more weight than when he won by 11 lengths at Newbury because he had a penalty for that.
"Aidan Coleman rides and he's got a very good chance. Hopefully all goes well."
Willie Mullins has a five-strong team, headed by the unbeaten ante-post favourite Blackbow, as he chases a ninth success in this race.
Gordon Elliott, who landed the prize 12 months ago with Fayonagh, relies on two-time bumper winner Felix Desjy.
David Pipe, successful in 2015 with Moon Racer, has an interesting contender in Know The Score while others with decent claims for the home team include Philip Hobbs' Crooks Peak, Jamie Snowden's Thebannerkingrebel and the Tom George-trained pair of Seddon and The Big Bite.