Yanworth has been ruled out of Saturday's Betfred-sponsored Contenders Hurdle at Sandown with a minor problem.
The Alan King-trained chestnut was due to have his prep race for the Champion Hurdle, but may now head straight to the Cheltenham Festival next month.
A winner of six of his seven starts over hurdles, his only defeat came to Yorkhill in the Neptune at the Festival 12 months ago and he beat The New One in the Christmas Hurdle last time out.
According to the ante-post betting he is the leading British-trained challenger for the Champion Hurdle this year.
Owner JP McManus' racing manager Frank Berry said: "He's just met with a small problem. He's tweaked a muscle in behind, it's nothing serious but he can't run this weekend.
"Hopefully it won't take too long to come right and we can get going with him again.
"Whether he runs again we'll just have to play it by ear, he could go straight to Cheltenham."