Willie Mullins and Ruby Walsh completed a Grade 1 double as Un De Sceaux produced a sensational front-running performance to win the Ryanair Chase.
Sent off a well-backed 7-4 favourite, Un De Sceaux was allowed to get on with things after tanking his way past early leader Uxizandre with over a circuit of the 2m 5f contest to run.
Un De Sceaux, whose only defeat over fences has come at the hands of the great Sprinter Sacre, went clear down the back on the final circuit, produced some stunning leaps and defied any stamina concerns by keeping on stoutly to keep his rivals at arms length.
The success means that his trainer Willie Mullins has now reached the major milestone of 50 Cheltenham Festival winners.
Winning jockey Ruby Walsh said aftewards: "I was a passenger. I got him back at the first fence down the back, but he attacked and jumped and he stayed.
"The jump at the last was special. He's a cracking little horse and he's so consistent, he must be a joy to own, he's a little tiger.
"He wants soft ground at two miles which is why we went two and a half miles on better ground.
"It's been a tough year for Willie but he's taken it great, I've worked for him since I was 17 so could eulogise about him all day."
Sub Lieutenant kept on best of the rest for second while Aso, the outsider of the whole field, ran a huge race to hold off hsi rivals for third.