Nicky Henderson believes Silviniaco Conti is the major obstacle in Bobs Worth's defence of his Betfred Cheltenham Gold Cup title.
The pair went toe-to-toe in the blue riband last term but the Paul Nicholls-trained Silviniaco Conti crashed out three fences from home when seemingly primed to challenge.
He tasted defeat on his return at Haydock this year but following his King George triumph at Christmas, Henderson expects him to be the main rival to Bobs Worth.
He told Racing UK: "Bobs Worth was the best horse last year. Silviniaco Conti did fall when you would have to say he would have been first or second.
"He's (Silviniaco Conti) been in great form this year, so he would almost certainly be the horse I'd be the most frightened of and I think the one plus we do have is that the Cheltenham hill plays to Bobs strengths and he loves it."
Bobs Worth was initially disappointing on his seasonal bow at Haydock but roared back to form with victory in the Lexus Chase at Leopardstown over Christmas.
He will have a fresh adversary in Irish Hennessy winner Last Instalment this time and jockey Barry Geraghty is wary of the threat he poses to Bobs Worth.
"I was fairly confident we'd see more of Bobs Worth's old self at Leopardstown and he was good," said Geraghty.
"He seems well at home, he's worked great and I'd be fairly hopeful.
"He (Last Instalment) has obviously been held up with injury, but I love the horse and I'd be very fearful of him.
"He jumps, he travels and he's a big, strong horse.
"He's a Denman/Kicking King-type model - he's a big beast."
Last Instalment may be rated as a major danger, but a late decision on his participation will be made as he must have some give in the ground.
"They watered on Wednesday night and the fog on Thursday morning will all help keep the moisture in," said trainer Philip Fenton.
"We are keen to run, we want to run, but we'll do what is best for the horse. I imagine we'll make a decision around 11.30am on Friday.
"Thankfully his form picked up from where he left off two years ago and he's as good as ever."
Should Last Instalment not run, owners Gigginstown House Stud will still have a representative in First Lieutenant, who chased home Bobs Worth in the Lexus.
Mouse Morris believes that run gives his charge solid place claims as he tackles the Gold Cup trip for the first time having finished second in the Ryanair at the 2013 Festival.
He said: "He has some good form in the book on his day and if Bobs Worth has a chance, we have an each-way chance.
"The trip won't be a problem - that's not a question mark in my mind.
"It might be he's not quite good enough, but he deserves to have a crack at the race."
Lyreen Legend was just touched off by Lord Windermere in the RSA Chase 12 months ago and his trainer Dessie Hughes could do with a change of luck after the fatal fall of Our Conor in the Champion Hurdle.
Hughes said: "He's only had two runs for one reason and another.
"He was very near the other horses and I think he's entitled to take his chance.
"There's not a lot between five or six of them so hopefully we'll be in the mix."
Lord Windermere has been slightly disappointing this season but trainer Jim Culloty is hoping a return to Cheltenham sparks him back to life.
"I am happy with Lord Windermere and he likes Cheltenham," said Culloty.
"I wish I was going to Cheltenham with a better run under his belt but for various reasons things have just not gone right for him this season.
"There is nothing wrong with him and he is going to Cheltenham in good old form."