Shane Lowry's eagerly-awaited professional debut fell miles short of what he was hoping for in the European Open at the London Club today. While Dane Anders Hansen was seven under par with one to play, the 22-year-old who won the Irish Open as an amateur 11 days ago slumped to a six-over 78.

As the day’s play drew towards a close, Hansen was a shot ahead of Swede Peter Hanson and South African Thomas Aiken — Hanson three days after holing in one to seal his place in the US Open — in the race for the €344,000 first prize.

Dubliner Peter Lawrie is two off of the lead, alongside India's Jeeve Milkha-Singh and England's Simon Khan, after he carded six birdies, including one at the 18th.

Rory McIlroy is three off the lead after a 69, while Graeme McDowell and Lowry’s playing partner Paul McGinley are two under after 70s.

Lowry signed his card and emerged with the words: “It’s over.”

Although he said he was not nervous, playing partner Paul McGinley sensed he was, and it would have been understandable.

“He has propelled himself into a different stratosphere,” said McGinley. “It was very difficult for him — it would be for anybody — but he is a class player and I didn’t see any weaknesses.”

Lowry, who before his shock 1000/1 victory had intended to stay amateur until after September’s Walker Cup, said: “I felt a bit flat and I’m glad to have it over.

“It’s the first day of many hopefully and there will be good days and bad days.

“I just got off to a bad start, four over after six, and didn’t feel myself to be honest. I knew it was going to be tough, it’s not an easy course by any means.”

He now faces a huge task just to survive the halfway cut, but he has good company in that.

World number five Henrik Stenson improved only two strokes on the 78 with which he started last week’s BMW PGA Championship and the horrendous last six months of 2005 US Open champion Michael Campbell continued with an 80.

Players Championship winner Stenson, who ran up double bogey sevens on both the 12th and 15th, said: “It’s not a crisis and I’m not really worried. There were a lot of good things even though I was not getting the scoring going.”

Troubled by neck and back problems, New Zealander Campbell has not made a cut since the Dunhill Links Championship in October and at Wentworth a week ago handed in scores of 79 and 82.

He had to wait only three holes this morning for it all to go horribly wrong again. Two lost balls off the tee at the long 12th led to a quadruple-bogey nine.

Hanson was playing with Campbell, but his confidence was sky-high after his Monday play-off hole-in-one and two twos were among his seven birdies.

“That ace was an enormous boost. It was a fantastic way to come into this,” he stated. “I’ve been struggling a bit with my long game, but everybody was congratulating me and you get so much energy out of it.

“I was striking it a lot better today and made a bunch of putts.”

Monday was also a good day for Aiken. Despite eight top-10 finishes in his last 10 starts, including seventh place at the CA world championship in Miami in March, it was only then that he was given an invitation to the tournaments.

Having lost his card by finishing only 131st on last season’s money list he is currently 25th and commented: “I’m fine for next year now, but just to keep playing this year I’ve obviously got to rely on invites.”

He was “only” level par at the turn, but then birdied six of the next eight holes.

Sergio Garcia came back from an opening double bogey to score a three-under 69, Rory McIlroy was on the same mark and both Lee Westwood and Colin Montgomerie one further back.

Montgomerie was asked what his first professional round was.

“A 76 in Switzerland which felt like 96,” said the Ryder Cup captain.