SANDWICH – Former champion Louis Oosthuizen remained atop the leaderboard of the British Open after the South African's scintillating second round of 65 saw him move to 11 under par at Royal St. George's on Friday.
His total of 129 through 36 holes is an Open Championship record low score.
Earlier, Collin Morikawa's 64 briefly took the American into the lead at nine under before Oosthuizen's charge which saw him pick up four shots in three holes between the 12th and the 14th.
Oosthuizen's victory in the 2010 British Open at St Andrews remains the lone major title of his career.
But he has been close to adding to that tally on several occasions with six second place finishes, including two this year at the US Open and US PGA Championship.
The 38-year-old was threatening a repeat of his British Open success of 11 years ago when he romped away from the field to win by seven shots.
His only dropped shot of the tournament so far at the 16th reduced his lead to two strokes.
"To have any record at the Open is always very special," said Oosthuizen. "I think I've played really well that the last two days.
"The last nine holes was as good a weather as you can get playing this golf course."
Morikawa showed no sign of inexperience on his Open Championship debut and just his second event on British soil after finishing 71st at last week's Scottish Open.
"I wouldn't be here through these two rounds if I hadn't played last week at the Scottish," said Morikawa.
"It was a huge learning opportunity. I went into last week wanting to win but I came out of it learning a lot more and that thankfully helped for this week."
The 24-year-old has already shown a liking for the big occasion during his short career, with three top-10 finishes in just seven previous major appearances -- including victory at last year's US PGA.
Royal St. George's saw the last debutant winner of the Open, when Ben Curtis triumphed in 2003.
But while Curtis was a rank outsider who never matched the heights of his golden week in Sandwich, Morikawa is already ranked fourth in the world.
Jordan Spieth made a similarly explosive start to his career, winning three majors in his first 18 appearances before tumbling to 92nd in the world earlier this year.
But the 2017 Open champion has rediscovered his form since winning the Texas Open in April.
Dropped shots at the third and 15th stalled his momentum, but he signed for a three under par 67 to remain in contention.
Johnson, Koepka, Rahm in hunt
A host of other big names made the most of the forgiving conditions under blue skies on England's south-east coast.
World number one Dustin Johnson carded a 65 to sit four off the lead on seven under alongside unheralded duo Dylan Frittelli and Scottie Scheffler.
Four-time major winner Brooks Koepka finished with three straight birdies to move to five under, alongside US Open champion and pre-tournament favourite Jon Rahm.
Bryson DeChambeau was forced into a climbdown late on Thursday when he admitted it was his play that "sucked" rather than his driver in his opening round following a backlash from club manufacturer Cobra.
The world number six received a few pantomime boos from spectators on Friday and just made the projected cut at one over par after a rollercoaster round of 70.
Rory McIlroy will be involved in the weekend's play thanks to a birdie on 18 for a second consecutive level par round of 70.
"I felt a little nervous going to that 18th tee. I knew I needed a par at least, but birdie to be comfortable," said McIlroy, who has a mountain to climb if he is to end his seven-year major drought.
But Phil Mickelson, who only two months ago became golf's oldest major winner at the age of 50 with victory in the PGA, won't be involved this weekend after missing the cut at 12 over following a miserable opening round of 80.