Stewart has already landed the staying crown four times with the incredible Big Buck’s, who remarkably won 18 successive races over timber after unseating Sam Thomas in the 2008 Hennessy Gold Cup at Newbury.
Saphir Du Rheu has also not yet grasped the nettle over fences, having failed to complete on two of his three chasing starts, most recently coming to grief when favourite for the Feltham at Kempton on Boxing Day.
The six-year-old will test his World Hurdle credentials in the Cleeve Hurdle on Festival Trials Day at Cheltenham on January 24.
“We’ve entered Saphir Du Rheu for the World Hurdle. He’ll revert to the smaller obstacles in the Cleeve Hurdle at Cheltenham a week on Saturday,” Stewart said.
“It’s ironic that Big Buck’s unseated Sam Thomas at Newbury before he reverted to hurdles and won the World Hurdle a record four times. Now I’m hoping Saphir Du Rheu, who also came to grief at Newbury, can do something similar.
“If he wins the Cleeve he could be second favourite for the World Hurdle.”
Saphir Du Rheu and his stablemate Zarkandar were among 36 entries for the stayers’ championship that are headed by last year’s winner More Of That, trained by Jonjo O’Neill.
Annie Power, runner-up in 2014, is one of eight from the Willie Mullins stable, although she has not run this season after a setback in November. She is also in the OLBG Mares’ Hurdle.
All of Mullins’ World Hurdle entries are Grade One winners, including Abbyssial, Briar Hill and Thousand Stars.
The 17 Irish-trained entries also feature Sandra Hughes’ Lieutenant Colonel, winner of the Christmas Hurdle at Leopardstown last month. That race saw an encouraging comeback in third from Noel Meade’s Monksland after two years off the track.
Jessica Harrington has entered Christmas Hurdle second Jetson, who took the Ladbrokes World Series Hurdle at Punchestown in April, while Kitten Rock has won four of his six starts over hurdles for Edward O’Grady but has yet to race beyond two miles.
Rock On Ruby, winner of the 2012 Stan James Champion Hurdle, is poised to try three miles for the first time after two victories over two and a half miles at Cheltenham this season.
Trainer Harry Fry said in his Stan James blog: “He’ll be lining up on the Thursday in the World Hurdle which will obviously be a big challenge, but one we’re relishing.
“Rock On Ruby is in great order and with such a good record at Cheltenham we’re looking forward to getting him there in one piece and seeing what happens. Whether he does stay the three miles or not, we’ll have to see.”
Whisper could be in line for a World Hurdle tilt after suffering defeat on his debut over fences at Exeter earlier this month.
The seven-year-old claimed the Coral Cup at Prestbury Park last March before striking at the top level in the Liverpool Hurdle at Aintree, but has failed to sparkle in his homework this term.
He made his belated return and chasing bow at Exeter on New Year’s Day, but had to make do with the runner-up spot behind Ceasar Milan and trainer Nicky Henderson is in favour of holding back his career over fences until next season.
He said: “I have put him in it (World Hurdle), simply because he had a run over fences the other day and he got beaten. That is probably not the problem, but he has come back with a bit of a problem and it will be another fortnight before he resumes work.
“Time is getting on and the fact that he didn’t win at Exeter means that he could just stay a novice over fences and we can just use the rest of the season over hurdles and go back over fences next season with a clear run.
“He’s a horse that hasn’t just sparkled yet this year and I’d be quite happy to leave the chasing for another year and just try and get him back over hurdles.
“The chances are he could easily turn up in the World Hurdle.”
Another likely World Hurdle candidate for the master of Seven Barrows is Beat That, who won Grade One prizes at Aintree and Punchestown as a novice last spring.
He has been similarly below-par this season, however, and could finish only sixth on his return to action at Cheltenham on January 1.
“Like Whisper, he hasn’t got into his groove yet this season. Neither of them, throughout the autumn, were doing what they showed us last year,” Henderson told BetRacingNation TV.
“I wasn’t expecting a great deal from Beat That at Cheltenham and the way he travelled through the race was very impressive. He jumped beautifully and was really on the bridle.
“He didn’t quite get up the hill. I can accept that in that it was his first run, but I wish he’d just finished it a bit stronger than he did.”
The Seven Barrows squad has two other possibles in Blue Fashion and Volnay De Thaix.
One of the least exposed entries is the Sandy Thomson-trained Seeyouatmidnight, who racked up a three-timer last season, culminating in the Rendlesham Hurdle at Haydock in February.
He rounded off the campaign when third to Beat That in the Sefton Novices’ Hurdle at Aintree in April, but has not run since.
Thomson, who trains at Duns in Berwickshire, said: “Seeyouatmidnight has obviously had a few hold-ups but none of them were anything major.
“The most recent one was a splint problem, but we have given him plenty of time and we should be able to get him to the track in good order.