Having run a remarkable race to finish second on his return to action at Exeter earlier this month, the six-year-old will attempt to go one better in the Grade One prize when racing over three miles for the first time under rules.
Nicholls said: "He could be a very exciting horse for the future and if I have another horse to compete in the King George and the Cheltenham Gold Cup in the future, he could be the one.
"I was thrilled with him at Exeter and he has come out the race so well it is like he has had two weeks off.
"He got left at the start, but that was one of those things. He jumped absolutely fantastic and did well to finish second in the end.
"They didn't go a great gallop, but he still had to make the ground up and that trip (two miles and three furlongs) was too short for him. He'll probably learn an awful lot from that run.
"He will come forward for that and we will go back over three miles now, he is a very exciting horse.
"He ran well in the Lanzarote last season and three miles will suit him far better. He is a high-class horse and we have just got to get some experience into him."
Nicky Henderson has earmarked the race better known as the Feltham for the exciting Santini.
The six-year-old will be bidding to back up his debut win over fences at Newbury and give the Seven Barrows handler his first success in the race since the victory of subsequent Gold Cup winner Long Run in 2009.
Henderson said: "I thought he was very good at Newbury, as I didn't think he was ready. I didn't want to go three miles first time out. I thought he would get tired, the ground was very soft and I had every excuse written on paper before we started.
"He actually warmed to it. The first part of the race was schooling and the second part was racing. He is a beautiful big horse - a very good-moving horse. He should enjoy Kempton. He never looked like a hurdler and anything he did last season gave us a lot of pleasure."
While Count Meribel may have work to do on official ratings, his trainer Nigel Twiston-Davies believes he can continue to take him by surprise after winning both his first two starts over fences.
Twiston-Davies said: "That's the way he is heading. He was good at Cheltenham and hopefully he will be even better at Kempton. I'm really looking forward to that one.
"He has surprised me all the time and hopefully he can keep on doing it."
