At Aragon on Thursday Jack Miller made his first public appearance since the announcement of his 2015 MotoGP move.

The 19-year-old Moto3 title leader will race an Open class Honda for the LCR team next year, meaning he is skipping the intermediate Moto2 category entirely.

Miller has a long term agreement with Honda, believed to be for three seasons.

"Of course I'm over the moon to have this opportunity," began the Australian. "I'm sure there are plenty of question marks, but Marc [Marquez] was a lot lighter and smaller than I am now. So physically-wise I think I can ride it.

"But I've only been on a road bike since 2009, not very long. So to be thinking I'm going to MotoGP next year is a big step. It's a long-term period that I've got and I believe that with the time and with the right attitude anything is possible.

"It's a motorbike. It's got two tyres and an engine. We'll do our best."

While Miller's age - he will be one month older than rookie champion Marc Marquez - and physical statue can be justified, the decision to miss Moto2 has generated plenty of criticism.

"Everybody has their own way," Miller answered. "All the guys here were very successful in the middle class and maybe I'll miss out on that. But for me, my goal is to go and ride with the best in the world and if you get handed that opportunity why not take it? I saw the opportunity and thought 'why not?'."

He added: "Sure I'll miss out on riding a 600. A bike similar in weight to MotoGP with less power and electronics. And a lot of experience as well. But I'm hoping that what I lose there, I'll gain by doing two years learning in MotoGP."

The Australian, who began this season without even a grand prix podium, revealed that talks with Honda began as far back as May, by which time he had won three of the opening five rounds. "It was a while back, I'd say around Le Mans was when we seriously started thinking about it. Maybe a little after."

Miller expects to make his MotoGP debut in November's post-race test at the Valencia finale. "I'm 99% sure the first ride is at Valencia and I'm 99% sure I'll be hitting the brakes at the finish line!" he smiled.

In terms of physical preparation, there is little he can do prior to the test without hampering his Moto3 chances, but Miller will then be working hard to build muscle over the winter.

"I'm going to have to train a lot, to go from an 80kg bike to 150kg. It's a big step. For sure physical training is the main thing. Try and put on muscle. But it looks like I'll be riding one after another [at Valencia]. Straight from Moto3 to MotoGP. I don't think I can put that much weight on overnight so we'll see what happens!"

A more pressing concern is defending his shrinking nine-point Moto3 lead over Alex Marquez, and 20-point advantage over Marquez's back-on-form Honda team-mate Alex Rins.

"It's starting to tighten up now and we have to start looking at it with five races to go, but we can't be careful especially now Alex Rins and Alex Marquez are going so fast," said the Red Bull KTM rider, who has only taken one win in the last eight rounds.

"They are both really going well and have got the Hondas working well. But we've had decent tests here and I think we can do a decent job. We'll wait and see tomorrow."

And should the title slip from his grasp? "Nobody is ever happy losing. I know I'm not, so my goal is 100 percent is to win the Moto3 title but there would be no use crying over spilt milk I guess."

Miller will ride one of the revised RC213V-RS Open class Hondas next year, which will be powered by this year's RC213V engine and replaces the current RCV1000R design.

Cal Crutchlow will be team-mate to Miller at the expanding LCR team, riding the factory class RC213V.

Alex Marquez and Rins will move to Moto2 next year.