It was the exquisite sound Rory McIlroy's golf ball made as it sailed through the air that prompted Khalid Yousuf to believe he was in the presence of greatness.
Yousuf, one of the UAE's leading Emirati players, can clearly remember that strange yet beautiful sound when the Northern Irishman, then a fellow amateur, struck his first tee shot on a Monday morning practice round at the 2007 Dubai Desert Classic.
If you had told Yousuf then that his playing partner would four years later write his name into golf history by dominating the 111th US Open to win his first major by eight strokes, the only surprise would be that his new found friend waited until he was 22 before making that breakthrough.
"I have played with a lot of really great golfers and the thing about them is not their swing, be it good or bad, but it's the ball striking that makes them stand out," said Yousuf, a member of the UAE amateur team who will compete in August's Nomura Cup in Fiji.
"Rory was the best I had seen, even back then before he turned pro. The noise the ball made as it flew through the air was amazing. It was like the sound of air being compressed, which may sound a bit crazy, but it was an incredible noise that only comes when a ball is 100 per cent perfectly hit.
"That's when I knew this guy was a special talent. His ball striking is the best there is and the rest of his game isn't too bad either.
"His first win was at the Desert Classic two years after that first round we had together, which showed me that I was right to think he had something about him."
That maiden victory came at the Emirates Golf Club where one of the professionals is Stephen Deane, a fellow Northern Irishman who was brought up 40 miles from McIlroy's hometown of Holywood.
Deane is six years older than McIlroy and can hardly remember a time when he didn't know about the local kid who was blessed with genius.
He said: "Rory was 12 when he first started to win amateur events, and 15 when he was beating most adults. He shot a record 61 at Royal Portrush from the back tees, at 16, so everyone knew this was someone to watch.
"He won every amateur title in Ireland and I first saw him play in the 2007 Walker Cup at Royal County Down, where I used to work. Everyone could see this guy just had the X-factor, not only what he did on a golf course, but how he carried himself off it while such a young man. He's just got it."
Andrew Whitelaw, the club manager at Emirates Golf Club, was delighted his venue has played its part in the Rory McIlroy story.
"Rory has always been great to watch from the days he played as an amateur in the Omega Dubai Desert Classic, to the day he won his first Tour event at Emirates Golf Club in 2009," he said.
"It was fantastic to see him win his first major and I am sure that this will be the first of many."
Nobody is more pleased than Yousuf, who has maintained a strong friendship with McIlroy. The two meet up whenever the Northern Irishman is in the UAE, either to play in a tournament or holiday in Dubai, which he has done for the past few years in the winter.
Yousuf said: "I first came across Rory at an amateur tournament in Scotland six years ago and there was a lot of buzz around him then. I actually didn't get to play with him because he was in the eight-handicap and under group and I was in the other group.
"My coach, Chris Parsons, knows him really well, and he introduced the two of us in 2007.
"We hit it off and became friends from that first round. I stayed up all night to watch him win in the early hours of Sunday morning and I'm so glad he did. It was one of the best golfing performances I have ever seen. After a while I stopped counting the number of records he was breaking."
Will this success change a golfer who everyone says is one of the good guys on tour?
"I think people will treat him differently," Yousuf said. "That can happen if you've just won a major, especially the way he did it. But they really should go approach him in the same way as before.
"I have met Rory's dad, Gerry, a few times and he's just like his dad in that he's a really good person. His life might change now but Rory won't."