South African Louis Oosthuizen set a testing clubhouse target in the second round of The Open Championship.
Oosthuizen, two shots behind leader Rory McIlroy overnight, added a 67 to his opening 65 for a 12 under par halfway total of 132 and a three shot lead over McIlroy, who was among the afternoon starters.
In the second group out today at 6:41am, Oosthuizen survived the wildly fluctuating weather to fire seven birdies and two bogeys, including three in a row from the fifth.
"When we got to the fifth the rain was coming down pretty hard and the back nine didn't look too bright at that stage, but we got lucky at 13 when the wind stopped and turned so we played the last five holes downwind," the 27 year old said.
"I knew I needed to keep calm throughout the round because I knew it was going to be a tough day and I'm very, very happy."
Oosthuizen, who was a collective 23 over par for his three previous Open appearances before this week, holed from three, four and ten feet for his hat-trick of birdies from the fifth, before driving the green on the 386 yard tenth to set up another birdie.
Further birdies on the 12th and 14th were sandwiched between two bogeys, but the former world junior champion also birdied the last with two putts from long range to complete an excellent round.
After ensuring a late tee time for Saturday afternoon - and only a second made cut in his ninth Major - before noon on Friday, Oosthuizen added: "I've never been done so early to be honest. There's more than a day (between rounds).
"I'll watch a bit of golf and try to relax."
American Ricky Barnes had looked like being Oosthuizen's closest challenger when he went out in 32 and birdied the tenth as well to reach nine under, but he then ran up a double bogey seven on the 14th after tangling with one of The Old Course's fearsome fairway bunkers.
England's Paul Casey, reportedly suffering from a bad chest infection, had nevertheless started with three straight birdies and picked up two more to reach the turn in 31.
Four straight pars from the tenth left The Ryder Cup star alone in third on eight under par.
McIlroy, at 21 looking to become the youngest winner of The Open Championship since Willie Auchterlonie in 1893, was not due to start his second round until 1:31pm, but World Number Three Lee Westwood was one under for the day and six under overall.
Westwood, who has been struggling with a torn calf muscle, picked up a birdie on the fifth and had carded 11 pars despite the occasional heavy showers and fickle breeze.
Casey was still eight under par when he reached the 17th, but was only five under by the time he reached the 18th tee.
After driving into heavy rough left of the fairway, Casey attempted to hack out sideways, but could only move the ball a few feet. His second attempt was more successful, but he missed the green with his fourth shot and three-putted from long range for a triple bogey seven.
That left 1989 champion Mark Calcavecchia alone in third place on seven under, the 50 year old having completed a flawless 67 in the first match out at 6:30am.
McIlroy began confidently enough, opening with a par four to remain nine under par and outright second, then also parred the second and third before play was suspended shortly before 2:40pm due to the strong winds, the main problem being balls moving on the most exposed greens.
Players had the option of completing the hole they were on when the hooter sounded, with Tiger Woods and Justin Rose making the short walk back from the first green to the clubhouse.
R&A rules official Ian Pattinson said: "We are trying to hold the players in position on the course. They are being directed to points of evacuation and held there in the hope that this blows over."
Play resumed at 3:45pm, a delay of just over an hour, with Woods and Justin Rose both completing three-putt bogeys on the first.
