Winner of the Albert Bartlett in 2016, Unowhatimeanharry was sent off 5-6 favourite for this race 12 months ago but had to settle for third place behind Nichols Canyon.
He will go off a bigger price this time round following defeats in Newbury's Long Distance Hurdle and the Long Walk Hurdle at Ascot.
"He is very much on target and it's all systems go," said the Seaborough trainer.
"He galloped on Monday and we were very happy with him and Noel Fehily is going to ride him again, which is great.
"He's a 10-year-old now, so he's up against it, but hopefully he'll run well in what looks an open enough race."
Unowhatimeanharry is among 19 horses left in the three-mile showpiece at the confirmation stage, and his owner JP McManus is also represented by the Alan King-trained Yanworth, who reverts to hurdling following a spell over fences.
Donna's Diamond has been supplemented by trainer Chris Grant at a cost of £15,000 following his victory in the Grade Two Rendlesham Hurdle at Haydock last month.
In what looks an open renewal, the market is headed by Jessica Harrington's Irish Champion Hurdle hero Supasundae, who took the Coral Cup at last year's Festival.
Fellow Irish trainer Willie Mullins has five possibles in Bacardys, Faugheen, Penhill, Augusta Kate and Let's Dance. Gordon Elliott's Apple's Jade completes the Irish party, although she is more likely to go for the OLBG Mares' Hurdle on Tuesday.
The Jedd O'Keeffe-trained Sam Spinner is a leading fancy thanks to his victory in the Long Walk, while last year's runner-up Lil Rockerfeller will try again for Neil King.
Nigel Twiston-Davies's stable stalwart The New One is set to tackle three miles for the first time as he makes his seventh consecutive appearance at the Festival.
Others in the mix are L'Ami Serge, Old Guard, The Worlds End, Wholestone, Colin's Sister and La Bague Au Roi.
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