Trainer Michael Halford expressed his delight at having the Italian on board his Beresford Stakes winner, who is owned by Dettori’s boss, Sheikh Mohammed.
Casamento was given the thumbs up to go to Town Moor following a spin on the gallops and after all the routine health checks.
“We’re happy with him and we’ve supplemented him,” said Halford.
“He’s quite fit so we just wanted to see that he was well. We checked him out, checked his blood and had him scoped. He’s fine.
“Frankie rides and it’s terrific to have him.
“I’ve spoken to Doncaster about the ground this morning. They say it’s good to soft, so that will be fine.”
Declan McDonogh was in the plate when Casamento was just pipped by Pathfork in the National Stakes and he partners Dunboyne Express for his boss Kevin Prendergast.
“They are pretty similar. Both are by Shamardal, show great heart and great toughness,” he said.
“It’s going to be a good race and both have got great chances. They are good two-year-olds.
“Dunboyne Express did a routine canter this morning. Everyone was really happy with him and he’ll do his last bit of work in the morning. He leaves on Thursday for the race. We couldn’t be happier with him.
“He’s a very uncomplicated horse and there’s no great mystery about him. You can ride him anyway you want and ground doesn’t really matter.
“I don’t think the trip will be a problem. He’s not a free horse and his pedigree suggests he’ll get a mile. That’s a help.”
And McDonogh is hopeful Dunboyne Express, who is unbeaten in two starts, will have the measure of Casamento.
“I think I can beat him. He’s a very good horse, I rode him in the National Stakes and he just lost out by a head. He went on and won the Beresford and I was second to him on a horse of Sheikh Hamdan’s (Mawaakef),” he told At The Races.
“But I wouldn’t swap my fella for anything. It will be close between them. They are two good horses.”
Casamento was one of three horses supplemented for the race along with the Michael Dods-trained Dubawi Gold and Karam Albaari from the John Jenkins stable.
Dunbyone Express was also among the 11 five-day confirmations while Aidan O’Brien is responsible for the three other Irish possibles.
The Ballydoyle trainer has left in Master Of Hounds, Seville and Treasure Beach.
Ed Dunlop decided to bypass last weekend’s Dewhurst Stakes with his unbeaten Solario Stakes winner Native Khan to wait for Doncaster.
Brian Meehan’s Titus Mills, the Michael Jarvis-trained Toolain and Zaidan from Clive Brittain’s yard complete the Trophy entry.
Victor Chandler have installed Casamento as the 7-4 favourite with Dunboyne Express next best at 4-1.
Racing Post Trophy, Victor Chandler bet: 7-4 Casamento, 4-1 Dunboyne Express, 9-2 Seville, 5-1 Native Khan, 8-1 Master Of Hounds, 14-1 Titus Mills, 20-1 Dubawi Gold, 20-1 Treasure Beach, 25-1 Toolain, Zaidan, 40-1 Karam Albaari.