Rockforce is out of the the Queen Mother Champion Chase at the Cheltenham Festival after breaking down in an after-racing gallop.

The gelding, who has a history of leg problems, went lame in front of the stands at Wincanton after completing a circuit of the course under Timmy Murphy, and was taken away in the horse ambulance.

His trainer Paul Nicholls was also left disappointed by the performance of Fadalko, his other candidate for the two-mile race on 13 March.

Fadalko, partnered by Jeremy Young and blinkered for the first time, disappointed in the headgear in his gallop with stablemate Cenkos.

Ad Hoc, who is being aimed at the Festival's William Hill Chase, pleased Nicholls when working well in the hands of Bobbie McNally after he proved too good for Phar From a Fiddle ridden by Polly Gundry.

Nicholls said afterwards: "It's a real shame about Rockforce as he was going so nicely in his gallop and seemed to be coming to himself.

"I was pleased with the others except Fadalko who didn't really take to the blinkers for the first time."