Willett, a golf scholarship student at Jacksonville State University, made a rousing start and won five holes on the spin from the third to surge into a commanding five-hole lead.

Having been forced on to the back foot early on, McIlory, who will play in next month's Open at Carnoustie, showed his class as he mounted a spirited rally.

He covered his final eight holes in five-under par as he narrowed his rival's lead to two holes but it was too little too late for the Belfast youngster and Willett staved off his menacing advances to seal a memorable win.

"Daniel had three birdies in the opening holes and was five under for 17 holes. When I was five down I was just concentrating on getting back to a reasonable score," said McIlroy.

"It's disappointing but I can't complain because he played well and made very few mistakes."

Willett said: "It's a great win for me and I'm delighted.

"I had a very good start but after I got to five-up he started to bite back. He's a quality player and I knew I would have to be at my best. This is a good scalp for me to have so early and hopefully I can build on this."

Just three of the seven Irish qualifiers made it into the last 32 with Co Louth's Simon Ward a 3 and 1 winner over Heysham's Jack Senior.

Lurgan's Gareth Shaw came through a preliminary round match against Adam Runcie but lost to Irish Close champion Shane Lowry on the 18th in the afternoon.

Peter O'Keeffe, Niall Turner and Niall Kearney also lost but Clandeboye's Jonathan Caldwell beat Ben Parker 2 and 1 and will face American Tom Glissmeyer next.

Turner was beaten 3 and 2 by Aussie Rohan Blizard with Kearney thrashed 5 and 4 by his former Jacque Leglise team mate Rhys Enoch.

Number one qualifier, David Horsey of Manchester, survived a titanic struggle with his England team-mate John Parry to win at the 21st hole.

Horsey, the 22-year-old West of England champion, thought he had sealed a narrow victory on the 18th green when he trundled in a birdie putt from over 30 feet. But Parry, the Spanish Amateur champion responded with a birdie putt of his own from 20 feet to force the sudden-death shoot-out.

His challenge was extinguished on the third extra hole, however, when he found the sand and Horsey two-putted for a par to seal the win.

Lloyd Saltman, a four-time winner on the amateur circuit in 2007, swept to a 3 and 2 win against Canada's Jason Wellings.

Jamie Moul, this season's Brabazon Trophy winner and a semi-finalist in last year's Amateur championship, overcame former English Amateur champion Paul Waring by 2 and 1.