Diamond Harry has been forced to withdraw from Boxing Day’s King George VI Chase (Long Run 5/4f), after the eight-year-old pulled up lame.

The 2010 Hennessy Gold Cup winner was due to clash with reigning champion Long Run and the revitalised Kauto Star, but trainer Nick Williams has been forced to pull him out.

It means eight will go to post for the high-quality Grade 1 contest, with Long Run looking for back-to-back wins in the Kempton showpiece.

But Kauto Star (10/1 Betfred Gold Cup 2012) did defeat the Nicky Henderson-charge last time out, in the Betfair Chase at Haydock in November - when Diamond Harry finished fourth.

Tony McCoy, who does not have a ride, partnered Kauto Star in last season’s King George and feels the 11-year-old will struggle to repeat his recent success.

McCoy said: “Kauto’s win in Haydock was a great spectacle for horse racing. I just think he has probably got it all to do to beat Long Run again.”

Melling Chase winner Master Minded, 2010 Charlie Hall Chase victor Nacarat, course winners Somersby and Captain Chris, and Golan Way make up the rest of the field.