Mullins has confirmed his six-year-old will step up to three miles for the first time at Cheltenham, which has set up a mouthwatering clash with Stewart’s four-times World Hurdle hero.
Stewart said: “I think it’s great they’ve decided to run Annie Power in the World Hurdle. It certainly spices the race up and it’s something for everyone to look forward to.
“I can fully understand why Willie has made this decision. He obviously doesn’t want to let her run against Quevega in the mares’ race and then would she be good enough to beat Hurricane Fly or whatever wins the Champion Hurdle?
“Annie Power is the up-and-coming rising star and she’ll be receiving 7lb (from Big Buck’s).
“We’ll find out whether she can stay three miles and also there is the question about the ground. Whenever I’ve seen her she’s been running on soft ground and by the Thursday of Cheltenham, it could be good, good to soft in places.
“We know Big Buck’s likes better ground, we know he stays and he has won the race four times, so we’ll just try to run our normal race.”
The man best placed to assess the merits of the two horses is Ruby Walsh, who partnered Big Buck’s to each of his four Festival triumphs, but will this year be in opposition aboard Annie Power.
“Ruby has ridden Big Buck’s in 19 races and won 18, so that is to his advantage and he’ll know exactly what will happen during the race,” said Stewart.
“They will no doubt be tracking one another, Ruby on Annie Power and Sam (Twiston-Davies) on Big Buck’s and then we’ll see what happens.”
Big Buck’s is out to regain his crown having missed last year’s Festival through injury and was not disgraced when finishing a close-up third on his return in the Cleeve Hurdle at Cheltenham in January.
Stewart feels if the anticipated improvement is forthcoming, Annie Power will have a lot on her plate to get the better of his pride and joy.
“In previous years we’ve had horses like Grands Crus, Dynaste and Oscar Whisky taking us on and none of them have been able to beat Big Buck’s,” he said.
“I’m very pleased Annie Power is taking us on. There is no point having a race where Big Buck’s barely needs to get into a gallop.
“Thousands of people will be paying good money to come to Cheltenham and watch the race, Ladbrokes are fabulous sponsors and everyone wants to see a good race.
“The two of them are joint-favourites, I believe, and I think that is probably about right.
“We couldn’t be happier with our horse and if Annie Power goes and beats him, then good luck to her, but she will have to improve a lot if Big Buck’s runs up to his best.
“Of course, he didn’t run up to his best in the Cleeve, but we think there are some good excuses for that, so we’ll see what happens on Thursday week.
“I have to say, I have never looked forward to the Festival more than I am at the moment.”
Meanwhile, connections of More Of That will wait as late as possible before deciding who will come in for the ride on the Ladbrokes World Hurdle candidate.
The Jonjo O’Neill-trained six-year-old burst on to the scene this season with an impressive display in a Haydock handicap in November.
A month later he was stepped up in class for the Relkeel Hurdle at Cheltenham, where he was a cosy winner under Tony McCoy.
But with McCoy riding the JP McManus-owned At Fishers Cross in the World Hurdle, More Of That now requires a new jockey.