The 15-year-old, who became the youngest winner of an official world-ranking event last October, is preparing to make his European Tour debut in this week's Abu Dhabi HSBC Championship.

And he warmed up for the tournament, which starts on Thursday, by playing a practice round with Koepka.

They played at the Abu Dhabi Golf Club and the American Ryder Cup star was impressed by the Dubai-based youngster.

"I know if I'd been in his situation I would have been as nervous as hell," the world's top-ranked player told BBC Sport.

"I was impressed with him, I really was - his attitude, the way he goes about things, the questions he asked. He's a good player and if he keeps progressing like he should he's got all the potential in the world.

"Whatever his goals may be, hopefully he reaches them," Koepka added.

'I asked him for a little match and, yeah, I beat him'

The practice round was arranged because Koepka is coached by Claude Harmon, who is attached to the Dubai training centre used by Hill.

The teenage amateur, who shot a final-round 62 to win the Al Ain Open last October, made the most of the opportunity.

"It was a great experience playing with him, obviously the best player in the world," Hill told me.

"Learning from him and watching him hit the ball was a great experience and hopefully I can take some of that learning curve into this week.

"I asked him for a little match on the last eight holes and, yeah, I beat him. Obviously we weren't going full out, but it's always nice to say you've beaten the world number one."

Hill, who was born in Surrey, splits his time between Dubai and Devon and is currently being taught online to prepare for his GCSEs in June.

But golf is his top priority for the next fortnight because his growing reputation has earned him starts here in Abu Dhabi and at next week's Dubai Desert Classic.

He is delighted to have spent time on the course with the world's best player.

"First of all I was obviously nervous, but he's such a nice guy there's nothing to be nervous about," Hill said.

"I asked him how he practises throughout the week to get some advice for that. I thought he would do a lot more random stuff but he said he just knocks ball on the range and that's how you get better, so it was quite interesting."

Playing alongside the elite of the European Tour will be a significant step up from the Middle East-based Mena Tour where the youngster has been competing.

But Hill is refusing to cap his ambitions for the coming couple of weeks.

"You can't aim low, you can't just aim to make the cut," he said. "You've got to aim high.

"I mean a top 10 would be nice but to be honest I've just got to go out there and play golf and see where that leaves me."