Tony McCoy fears he could have made the wrong choice in picking At Fishers Cross over More Of That for the World Hurdle.
McCoy has stayed loyal to the Rebecca Curtis-trained At Fishers Cross, a Festival winner 12 months ago in the Albert Bartlett Novices' Hurdle, despite Jonjo O'Neill's More Of That being unbeaten.
However, the latter has never run over three miles, and McCoy admitted that was a factor.
Writing on his blog for Cheltenham racecourse, McCoy said: "It was a tough decision, I rode More Of That this morning and he is flying.
"I was on him thinking 'maybe I should be riding him at Cheltenham' but the only worry I have is that it will be his first run at three miles.
"Looking at the race with Annie Power now in it, Paul Nicholls will have four runners and the best stayer of them all is Big Buck's - so it isn't going to be a slowly-run World Hurdle.
"Big Buck's is the ultimate stayer - he will stay and then stay a bit more. I know Zarkandar has a different owner but Andy Stewart owns half of Salubrious and all of Celestial Halo and Big Buck's so I do think it will be a very true-run race."