Sizing Europe bids to retain his Queen Mother Champion Chase title at the Cheltenham Festival on Wednesday.
The 10-year-old, trained by Henry de Bromhead, won at odds of 10-1 last year but is a strong favourite this time.
He renews rivalry with fellow Irish challenger Big Zeb, winner of the Cheltenham contest in 2010 but five lengths back in second last year.
Finian's Rainbow and Kauto Star's half brother Kauto Stone are among others set to line up.
Sizing Europe is looking for a hat-trick of Festival successes, having won the Arkle Chase in 2009.
He showed his well-being when beating Kauto Stone by eight lengths to win the Tingle Creek Chase at Sandown in December and trounced Big Zeb by 15 lengths at Punchestown last month.
Big Zeb, whose trainer Colm Murphy will hope his horse can get closer at Cheltenham, boasts a reliable record, finishing in the first two in his last 10 races.
Finian's Rainbow, for Nicky Henderson, was second in the 2011 Arkle Chase.
Kauto Star will bid for a third Gold Cup success on Friday and trainer Paul Nicholls will hope some of the family talent has rubbed off on Kauto Stone.
The eight runners also include Gauvain, I'm So Lucky, Realt Dubh and Wishfull Thinking.
The feature race is preceded by the RSA Chase (1440) for top novices, where Grands Crus is expected to be a hot favourite for David Pipe.
Bobs Worth (Nicky Henderson) and last year's Neptune Novices' Hurdle winner First Lieutenant, trained by Mouse Morris, are also in the line-up.
Henderson's Simonsig is a leading fancy for this year's Neptune (1405).
The opening Diamond Jubilee National Hunt Chase (1330), for amateur riders, will see Sam Waley-Cohen - the jockey who won last year's Gold Cup on Long Run - ride Alfie Spinner.
Carlito Brigante, an easy winner of the Coral Cup (1600) last year for Irish trainer Gordon Elliott, is being lined up for a repeat victory.
Alan King saddles leading hope Vendor in the Fred Winter Juvenile Handicap Hurdle (1640), while two runners for Irish trainer Willie Mullins in the concluding Champion Bumper (1715) will be keenly followed.
Champagne Fever and Pique Sous are the entries for Mullins, who has won the race six times in the last 15 years although his last success came in 2008 with Cousin Vinny.
SPORTINGBET.COM QUEEN MOTHER CHAMPION CHASE two miles, 1520 GMT, Wednesday (Racecard number, odds, horse's name, age, weight, trainer, jockey, approximate odds)
1 22-1112 BIG ZEB 11 11-10 Colm Murphy IRE 9-2 Robbie Power
2 1121-12 FINIAN'S RAINBOW 9 11-10 Nicky Henderson Barry Geraghty 5-1
3 0-1F1F3 GAUVAIN 10 11-10 Nick Williams Noel Fehily 25-1
4 460-053 I'M SO LUCKY 10 11-10 David Pipe Tom Scudamore 40-1
5 103-120 KAUTO STONE 6 11-10 Paul Nicholls 16-1 Ruby Walsh
6 2113-12 REALT DUBH 8 11-10 Noel Meade IRE 20-1 Paul Carberry
7 1-21211 SIZING EUROPE 10 11-10 Henry De Bromhead Andrew Lynch 10-11
8 1-16526 WISHFULL THINKING 9 11-10 Philip Hobbs Richard Johnson 14-1
Pinstickers' guide: Sizing Europe was an impressive winner last year and has looked unstoppable in his last two outings. Several have chances of making the frame.
Verdict: 1 Sizing Europe 2 Finian's Rainbow 3 Kauto Stone