Bryan Cooper made the most of his spare ride on Roi Du Mee, who ran out an impressive winner of the JNwine.com Champion Chase at Down Royal.
Cooper switched to Gordon Elliott's charge after his original mount Quito De La Roque was withdrawn and duly made all in the Grade One contest over three miles.
First Lieutenant, ridden by Davy Russell, carried the first colours of owners Gigginstown House Stud, but 12-1 shot Roi Du Mee, fit from two starts last month, altered the script.
Cooper was able to dictate matters on the eight-year-old and Roi Du Mee steadily pulled well away from his rivals to land the spoils in emphatic fashion from the gallant Sizing Europe, who was finishing second in the race for the third time.
Elsewhere, Elliott landed the Billecart-Salmon Handicap Hurdle for the second year in a row, as Time To Work (14-1) followed in the hoofprints of Beef To The Heels, and Moonshine Lad completed a treble for the trainer in the Daily Mirror (Pro/Am) Flat Race.
Paul Nicholls claimed the Powers Irish Whiskey Chase for the sixth consecutive year courtesy of Rolling Aces.
The British raider was being challenged for the lead by Argocat when that one got the last all wrong, paving the way for the 9-4 favourite to pass the post two lengths clear of Toner D'Oudairies.
Guitar Pete (11-4) took his jumping record to two wins from three starts with victory in the Value Cabs 3-Y-O Hurdle.
Dessie Hughes' juvenile was conceding weight all round but was always in the front rank and quickened in the straight to beat Gerdago by seven lengths, with favourite Gitane Du Berlais only third.
Smart bumper performer Gilt Shadow made a successful start to his jumping career in the Tayto Group Maiden Hurdle.
Second in the Grade 1 NH Flat Race at the Punchestown Festival, Stuart Crawford's 11-4 shot took up the running before the third-last flight and stuck to his guns well to see off Rock The World by eight and a half lengths, while Ruby Walsh steered Twin Plan to the spoils in the Rainbow Communications Handicap Chase.