In a week dominated by Rory McIlroy's ill-advised off-course activities, it was somehow fitting that Thorbjorn Olesen claimed the lead after the first round of the Aberdeen Asset Management Scottish Open.

McIlroy's worst fears were confirmed on Wednesday when he was forced to pull out of his Open Championship defence due to an ankle ligament injury suffered while playing football.

And although that was described as an "unforced error" by former US Ryder Cup captain Paul Azinger, Olesen could certainly sympathise with the world number one after injuring himself getting off a camel in Dubai last year.

"I was with a few mates and went on a camel and when I had to jump down I just pulled a muscle in my groin," Olesen admitted after a flawless opening 63 at Gullane. "It took a few weeks before I could properly walk again. But that's what happens. You've got to have a little bit of fun.

"I know of a lot of footballers had to stop because they had groin problems. It can come any minute almost so I just keep training in the gym and keep getting results and stretching and hopefully it will not come back.

"I know Rory has very good people around him, so I'm sure he'll get ready very soon."

Olesen, who finished sixth on his Masters debut in 2013, also discovered a tendon problem in his left hand over the winter but battled on for four events - missing the cut in the last three - before undergoing surgery at the start of February.

"It's been a tough time but I keep working on the right things and hopefully it will come," said the 25-year-old, who lost a play-off for the Mauritius Open in May in his first event back after three months on the sidelines. "I showed today I can still shoot low rounds.

"I hit almost every green - only missing the 18th - and hit a lot of fairways, which was the key."

At seven under par Olesen led by two shots from a six-strong group including American Ryder Cup player Jimmy Walker and English pair Matthew Nixon and Richard Finch, with Ireland’s Shane Lowry and Graeme McDowell, defending champion Justin Rose, Rickie Fowler, Matt Kuchar all four under and tied for ninth.

Padraig Harrington, meanwhile, finished on two under while Damien McGrane was one under after a 69.

Michael Hoey finished the day level with a round of 70 but Paul McGinley had a round to forget coming in with a six over 76.

Even three-putt bogeys on the last two holes could not dampen McDowell's enthusiasm for a welcome return to form in the week he slipped out of the world's top 50 for the first time in five years.

McDowell's sole top-10 finish on the European Tour this season came in February and he missed the cut when bidding for a third successive French Open title last week, a second round of 78 being his worst score in 32 rounds at Le Golf National.

"I feel as if in an attempt to improve some things in my technique, I've actually got worse" - Graeme McDowell

The 35-year-old revealed he and coach Pete Cowen had been examining videos of his swing from 2010, the year he won the US Open at Pebble Beach and holed the winning putt in the Ryder Cup at Celtic Manor.

"I'm trying to get back to basics and we have narrowed my stance and used my body to swing the club how I used to," McDowell added.

"I feel as if in an attempt to improve some things in my technique, I've actually got worse.

"It was also nice to get back on a course that gives you a few opportunities in benign conditions. I just need a few low numbers to get my belief and confidence back and today will go a long way towards that."

Rose admitted he was beginning to lose his patience after letting a number of opportunities slip, but birdied the 16th and responded to a bogey on the 17th with another birdie from 20 feet on the last.

And the resulting 66 certainly justified his decision to practice at St Andrews on Monday and Tuesday this week and rely on caddie Mark Fulcher to plot a route around Gullane.

"He's doing the hard work and making my schedule a lot easier," Rose said. "It was a pretty stress-free round and I did not burn up too much energy out there."

Almost half the 156-strong field broke par with five-time major champion Phil Mickelson - who won the Open one mile down the road at Muirfield in 2013 - carding a 69 after struggling on the greens.