Yesterday morning's rainy squalls and strong winds ground down many of the 156 starters the Royal County Down, particularly Rory McIlroy who shot 80.
In the afternoon, the worst of the weather had passed, allowing some easing of the burden on the Tour players, including Ireland's Pádraig Harrington who rocketed to the top of the leaderboard with his four-under-par 67.
Harrington, whose victory in the Honda Classic in March was his first on a major tour since the 2008 US PGA, was one over par after 10 holes before carding five birdies in the next six to finish one shot ahead of former Ryder Cup team-mate Soren Hansen to share the lead with German Maximillian Kieffer.
"After nine or 10 holes I thought to myself 'C'mon, we've got to hit a good shot, no need to be afraid,'" said Harrington, who lasted just two holes at Wentworth before pulling out with a shoulder injury, but received intensive treatment and narrowly missed out on qualifying for the US Open four days later.
"I know from experience now that I'm in a position where there's many ways of competing in this tournament. I've two options; play great from now on and try and get away from the field or play average and fight it out on Sunday afternoon."
Major winner Graeme McDowell and former Ryder Cup captain Paul McGinley (pictured)both finished with one-over-par 72s and were relieved and pleased with their solid start.
They fought the course to a standstill and emerged from their morning round battered, bruised, but in decent shape and full of admiration for this championship venue.
"In those conditions, this course is a beast, borderline evil in this type of wind. We don't get to experience these conditions very much, this is raw, this is what it's all about," McDowell said.
"You could put the grandstands up and play the (British) Open here. Between showers and gusts, it's playable, but as the fronts roll through, it's very difficult. Anything around par is a very good score. It's all about not blowing yourself out of the tournament."
McGinley has a course design business as well as his playing career, and in each of those departments, Royal County Down has soared in his estimation.
"It's a magnificent test of golf. If you put all the Open courses together, in Ireland or Britain, in my opinion, that's the toughest test of golf. It requires an incredible skill set to get around that golf course.
The third of the host nation's recent major winners, European Ryder Cup captain Darren Clarke, lies well back on four over, but his compatriot Michael Hoey fared better on level par.