The Philip Fenton-trained six-year-old is 7-1 second favourite on the strength of a 13-length victory at Navan in December.
O’Connell, who has partnered the gelding in all of his three starts, is set to keep the mount.
The 22-year-old is an integral part of Fenton’s County Tipperary yard and has enjoyed a fruitful campaign in Ireland, lying third in the amateurs’ table with 14 victories, behind Patrick Mullins and Nina Carberry.
“I’ve been pre-booked to ride Dunguib in the Weatherbys Champion Bumper and hopefully we can both get there in one piece,” said O’Connell.
“It’s amazing to keep the ride on him. Bumpers are confined to amateurs in Ireland but they are open to professionals in Britain so Philip and the owners would have been under no obligation to let me ride him at Cheltenham.
“To be able to go to the Festival with a real live chance of a winner is a dream come true.
“This will be my first time riding in England and there’s no bigger place to make your debut.
“I was actually due to ride a horse for Philip at Cheltenham last year but, unfortunately, the horse was balloted out.”
Meanwhile three past winners – Kingscliff (2003), Sleeping Night (2005) and Amicelli (2008) – are among 43 entries for the Christie’s Foxhunter Chase on Friday week.
Ante-post market leader is the prolific point-to-point scorer Cappa Bleu from Sheila Crow’s yard, while the second favourite, the Eugene O’Sullivan-trained Juveigneur, is among nine Irish entries.
John Costello’s Carronhills and Brian Hamilton’s Chief Oscar are others carrying major Irish hopes.
Champion British trainer Paul Nicholls, seeking his third success in the contest, could be represented by Royal Auclair and Ofarel D’Airy.
Other possibles include the Venetia Williams-trained Limerick Boy and Murphy’s Cardinal from the Noel Chance stable.
Entries closed a week later than originally advertised to give horses extra time to qualify after a large number of point-to-points and hunter chases were abandoned in the last two months.
Nigel Twiston-Davies expects Imperial Commander to tackle the Ryanair Chase rather than the Gold Cup.
The Paddy Power Gold Cup winner stepped up to three miles for the King George VI Chase but faded tamely and has not been seen since.
The trainer has been weighing up both races and is hoping that his lengthy break will have done him the world of good.
“He’s been great, he’s had a bit of time off and we’ve freshened him up as he goes well fresh,” said Twiston-Davies.
“We think he will probably be going for the Ryanair but he’ll be declared for both.
“He won a handicap (Paddy Power) as he pleased and the horse that was second to him there (Barbers Shop) is going for the Gold Cup so the world could be his oyster,” he told At The Races.
Imperial Commander is around an 8-1 chance for the Ryanair while he can be backed at around 33-1 for the Gold Cup.
United will complete her preparation for the David Nicholson Mares’ Hurdle at Cheltenham next Tuesday with a final piece of work today.
The eight-year-old is generally 4-1 third favourite for the two-and-a-half mile contest following her latest success at Ascot in January.
“She’s been working regularly and she’s going to work tomorrow. That will be her last bit, everything’s gone right with her,” said trainer Lucy Wadham.“She’ll be staying here at Newmarket to work. We’ve got 65 miles of gallops to choose from, so she’ll definitely be working at home.
“United’s in great order, I’m very happy with her.”