Graeme McDowell was joined by home pair Scott Jamieson and Pete Whiteford at the top of the leaderboard after firing a second round 64 to set up the possibility of a second Barclays Scottish Open title in four years.
Last year's US Open Champion stands 11 under par at halfway and when play was suspended for the day after two thunderstorm delays he was sharing the lead with Scots Whiteford and Jamieson.
Luke Donald and Lee Westwood, World Numbers One and Two, and Open Championship-chasing Colin Montgomerie were among those affected by the hold-up.
Donald and Westwood managed 11 and nine holes respectively and both will resume on seven under, while Montgomerie is one further back and only joint 25th now in pursuit of the top five finish he needs for Sandwich.
McDowell was only joint 30th when he resumed on three under, but had an eagle and two birdies in his first four holes - "a dream start" - and then added four more birdies.
"We realised conditions were going to be easy and it was going to be there for the taking a little bit,” he said.
"The course obviously doesn't offer much of a challenge off the tee and there's chances galore, but the greens are tricky.
"I think the balance is just right. If we had been coming to a brutal test here maybe you'd be mentally worn out."
Whiteford and Jamieson were both round in 66, but the latter stood four clear at one point and was bitterly disappointed to double bogey his penultimate hole, the 218 yard eighth.
The 27 year old is in his rookie season on The European Tour, but has already had four top-six finishes and said: "It would be a dream come true to win your first tournament on home soil - beyond all expectations."
Jamieson does not have a place in the Sandwich field yet, but top five on Sunday could do it for him.
“The course is fantastic,” he said. “Obviously playing well helps. I think every hole is really well defined.
“All of the fairways are kind of green and you've got the longer grasses with a kind of brown colour, you play through dunes. But it's just a really nice mix. The par fives and the short par fours you feel that you can attack if you like and pick up birdies.
“They are all very tricky greens, and there's tricky areas around the greens. I think patience is probably an important thing on this golf course, as well.”
Whiteford, three years older, came through the qualifier at Sunningdale to earn an Open Championship debut at the 15th attempt.
"It's my third year out here, so I know the golf courses and the faces. What Scott's doing in my opinion is phenomenal - every week is a new week to him."
Spain's Jose Manuel Lara was one behind, while another Scot - 1999 Open Champion Paul Lawrie - matched McDowell's 64 to charge to nine under.
Justin Rose, Padraig Harrington and America's World Number Eight Matt Kuchar are eight under and Ernie Els one further back, while Phil Mickelson had to come home in 32 with an eagle and two birdies for a 67 that lifted him to four under.
That was a shot inside the expected cut mark, but that was with half the field still to complete their rounds on Saturday morning.