The six-year-old will put his unbeaten record on the line as he looks to give trainer Willie Mullins, who is also represented by Sharjah, a sixth victory in the two-mile curtain-raiser.
"I think the rain is definitely in his favour as he handles the soft ground and he stays further than two miles," said assistant trainer Patrick Mullins.
"He has travelled over fine and has had a good preparation. Obviously he has got to improve from his current performances, but he is more than capable of doing it.
"It looks an open renewal but Kalashnikov sets a fair standard and Mengli Khan is a Grade One winner. He is a different type to a lot of our previous runners in the race."
Watch Patrick Mullins discuss Getabird's chances in the Supreme Novices' Hurdle
Of Sharjah, he added: "I think he would prefer drier ground, and that would be the concern. It was just drier ground when he ran very well over Christmas."
Amy Murphy is looking forward to seeing Betfair Hurdle hero Kalashnikov on the biggest stage of them all, but recent rainfall at the track has slightly tempered optimism.
The Newmarket handler said: "He was impressive at Newbury. Under 11st 5lb, as a novice, it was an extremely good performance.
"He was a big baby going into the race. He'd never seen anything like that before but we were delighted with him.
Watch Rachel Casey's interview with Amy Murphy in Newmarket
"He seems in great order at home. We'd rather it wasn't raining the way it is, but there's nothing we can do about that and at least with it being the first race, we'll be running on fresh ground.
"We're excited to be there. For a yard the size of ours to have two horses with live chances going to Cheltenham is fantastic and we're very much looking forward to it."
Tom George feels Summerville Boy will have plenty in his favour as he looks to follow up his victory in the Tolworth Hurdle at Sandown.
George said: "His form is rock-solid. You can put a line through his first three runs as they all went at a canter and he needs to come off a strong gallop.
"The first time he got that was in the Tolworth, which he won fair and square. It didn't surprise me what happened.
"He needs settling in behind a good gallop and he will get that here. He coped with the ground well at Sandown, but I'm not saying he needs heavy ground as he will go on good ground as well."
Gordon Elliott is optimistic Mengli Khan will be seen in a better light after finishing second behind Getabird at Punchestown.
He said: "I thought Getabird was very good in Punchestown, but I don't think Mengli Khan was himself.Mengli Khan will be ridden by Jack Kennedy
"The third and fourth horses were too close to him and he looked a little bit light afterwards.
"I still think it's going to be hard to beat Getabird, but I think we'll have a different horse at Cheltenham, all being well."
Kim Bailey feels First Flow is capable of featuring at the finish after his prayers for rain at the track were answered.
He said: "He deserves to have a chance to go there and soft ground will certainly be a huge benefit for him.
[(full)Watch Replay](//) First Flow's last two victories were on heavy ground
"He's stepping up into a different league but he's done nothing wrong so far.
"I've always looked upon him as a horse that wants further. We started him off at two miles because he was always quite free at home."
Warren Greatrex believes last year's Champion Bumper fifth Western Ryder could be one of the dark horses in the race.
He said: "There is more rain coming ahead of Wednesday and I think it will be better running in the first race on the first day on the fresh ground.
"He is in seriously good form and he could be one of the forgotten horses in the race."
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