Sprinter Sacre and Sire De Grugy, the last two winners of the Betway Queen Mother Champion Chase, head a stellar field of 11 horses for the two-mile showpiece at Cheltenham on Wednesday.
Sprinter Sacre was a deeply impressive winner in 2013 and though a heart problem prevented him from defending his crown 12 months ago, Nicky Henderson's top-class performer is back in a bid to regain the title.
The nine-year-old made an encouraging return when second to Dodging Bullets in the Clarence House Chase at Ascot in January.
Sire De Grugy claimed gold last term, but it has not been plain-sailing for him, either.
Gary Moore's nine-year-old disappointed on his comeback when unseating rider Jamie Moore in the Game Spirit Chase at Newbury, but got back on track with a fine weight-carrying performance at Chepstow last month.
Paul Nicholls has a powerful in-form duo in Game Spirit scorer Mr Mole and Dodging Bullets, winner of the Tingle Creek as well as the Clarence House.
Willie Mullins' dual Festival winner Champagne Fever heads the Irish challenge, with Henry de Bromhead doubly represented with Special Tiara and the veteran Sizing Europe, who landed this race in 2011.
The Tony Martin-trained Savello, Nicky Richards' Simply Ned and Somersby from Mick Channon's yard are set to take their chance, while Gordon Elliott's novice Clarcam has also been declared for the Arkle on Tuesday.
Balder Succes was the only withdrawal at the 48-hour final declaration stage.
