Kauto Star will aim to win a record fifth King George VI Chase at Kempton Park on Boxing Day, after his entry was confirmed by trainer Paul Nicholls.
Nicholls said: "I've had a chat with Clive [owner Clive Smith] and we're going to run Kauto and Master Minded."
The 11-year-old defied the critics by beating Long Run to win the Betfair Chase at Haydock three weeks ago.
Amateur jockey Sam Waley-Cohen has avoided a ban that would have stopped him from riding Long Run on the day.
Waley-Cohen took the wrong course in a race at Fakenham on Monday but a 12-day suspension applies only on days of amateurs-only races, so it will not start until 1 January 2012.
Meanwhile, Nicholls explained that the unpredictable lifespans of racing horses helped sway his and owner Smith's decisions.
Ruby Walsh will ride Kauto Star, with Daryl Jacob aboard Master Minded.
"We saw with Tataniano and Denman recently how the smallest of injuries can end seasons and careers, and that brought into sharp focus that sometimes you have to seize the moment with racehorses," he added.
Amy Starkey, Kempton Park's managing director, said: "This is brilliant news. We are delighted for all Kauto's fans who will be at Kempton Park on Boxing Day.
"It will be an incredible occasion when Kauto takes on Long Run. It's the 'must see' horse race of the season."
Kauto Star, stablemate Master Minded and 2010 winner Long Run are among the 15 horses that could take part in the £180,000 showpiece.
Irish challenger and Arkle Trophy winner Noble Prince and trainer Henrietta Knight's Somersby may also compete in the famous festive race.
RECENT KING GEORGE VI WINNERS
2010: Long Run
2009: Kauto Star
2008: Kauto Star
2007: Kauto Star
2006: Kauto Star
2005: Kicking King
2004: Kicking King
2003: Edredon Bleu
2002: Best Mate
2001: Florida Pearl
2000: First Gold
