The 2014 World Hurdle hero was sixth in the Gold Cup at Cheltenham last season before being pulled up in the Grand National and was having his first start since that run at Aintree.
The nine-year-old finished a well-beaten sixth as Outlander took top honours, with only the very disappointing Our Duke behind him.
O'Neill said: "He ran OK, but that is all he did do. I was really happy with him going there, he was in really good form at home.
"I was a shade disappointed, if I am honest. He is nine now and has had his problems and he is probably not the horse he used to be.
"We will probably have to go the handicap route now."
Select any odd to add a bet