Little-known American Steve Marino, making his British Open debut, set the target in the clubhouse on five under par early in the second round on Friday.
Typical Turnberry weather greeted the players as murky skies, light drizzle and fresh winds moved over the Ailsa Course but the 29-year-old Marino defied the elements by sprinkling four birdies and an eagle in a two-under 68.
The world number 77 moved one behind Japan's Kenichi Kuboya who was leading the way on six under through six holes.
American Tom Watson, 59, who stole the first-round spotlight with a sizzling five-under 65, and world number one Tiger Woods (71) were late starters.
Marino, who has compiled three top-10 finishes on the PGA Tour this season, mixed the outrageously good with the indifferent as he swapped three birdies for three bogeys on the front nine.
He holed a 116-yard approach shot with a sand wedge at the third, sank a 30-foot putt for another birdie at the fifth and then saw his bunker shot go straight into the cup for a two at the par-three sixth.
On the inward half Marino dropped a stroke at the 10th before following a birdie at the 14th with an eagle three at the 17th where he coaxed in a curling 20-foot putt.
"It was one of the hardest courses I've ever played today," Marino told reporters. "It was like a totally different course and played so difficult out there with the wind early and the rain.
"I really don't think I could have shot one stroke less today."
Marino, awarded a place in the field when Japan's Shingo Katayama dropped out with a back problem on Sunday, had not played on a links course until this week.
"(Links golf) is awesome, I'm just having a blast," he said. "It was probably one of the best scoring rounds I've ever had."
Elsewhere, birdies were scarce as the glorious sunshine of Thursday gave way to conditions more traditionally associated with a seaside layout.
Overnight leader Miguel Angel Jimenez was among the players who struggled to cope with gusts of 18-mph (29-kph) sweeping across the Ayrshire layout.
The pony-tailed Spaniard limped to the turn in 39 as he plunged from six under to two under overall.
Jimenez's woes were summed up by a bunker shot at the seventh.
Trying to repeat the brilliant recovery from sand achieved by South African Retief Goosen 24 hours earlier, he knelt on the edge of a trap but barely made contact as his ball remained in the hazard.
Britain's Ross Fisher finished his round with a flourish as a hat-trick of birdies from the 15th helped him card a 68 for 137, three under.
By contrast Fisher's playing partners Ben Curtis and Mike Weir were glad to see the back of the course.
Curtis, the 2003 champion, slid to an 80 to plunge from five under to five over and former U.S. Masters winner Weir also finished on 145 after a 78.