AP photo by Peter Morrison / Louis Oosthuizen acknowledges the crowd after making an eagle putt on the 14th hole at Royal St. George's Golf Club during the second round of the British Open on Friday in Sandwich, England.

SANDWICH, England — Louis Oosthuizen set the British Open's 36-hole scoring record and is halfway to ending his frustrating stretch of a half-dozen runner-up finishes since winning his lone major championship more than a decade ago.

Now all he has to do is hold off a formidable cast of contenders this weekend at Royal St. George's Golf Club.

On a day of pleasant summer weather that took the fear out of the links off Sandwich Bay, Oosthuizen broke away from a three-way tie with a birdie-birdie-eagle run that started on the 12th hole. He shrugged off his first bogey of the week for a 5-under-par 65 and a two-stroke lead Friday.

Oosthuizen, looking as calm as the conditions, was at 11-under 129, breaking the tournament's 36-hole record set by Nick Faldo in 1992 at Muirfield and matched by Brandt Snedeker in 2012 at Royal Lytham & St. Annes.

Collin Morikawa, a 24-year-old who won last year's PGA Championship for his first major title, shot a 64 in the morning and was two shots behind. Another shot back was fellow American Jordan Spieth (67), going after his fourth major as he approaches his 28th birthday.

Lurking was two-time major champion Dustin Johnson, the No. 1 player in the Official World Golf Ranking, who shot a 65 and was tied for fourth, four strokes behind Oosthuizen.

"The game is good, but I know it's a really good leaderboard," the 38-year-old Oosthuizen said. "I'll have to play good golf this weekend if I want to come out first."

Harris English made a tremendous turnaround to ensure he would be around for the weekend. The former Baylor School and University of Georgia standout was only at par for 36 holes, which left him tied for 53rd, but he generated one of the biggest leaderboard leaps of the day by moving up 84 spots.

He had two bogeys in his first five holes of the second round but didn't drop another stroke and began to reverse his fortune with a birdie on No. 9. He had three more on the back nine, including the par-4 18th — that gave him six birdies for the day, with his first on the opening hole — but the highlight was his eagle on the par-5 14th.

It all added up to a 65 and a 10-stroke improvement from the first round, allowing him to make the 1-under cut with room to spare.

"I don't like missing cuts, and I especially don't like missing cuts at the Open. This is one my favourite tournaments," English said, adding that he was "lucky to get on the right side of draw."

Chattanooga native Keith Mitchell, who also played at Baylor and Georgia, followed an opening 68 with a 76 that included three straight bogeys to close his round and his week at Royal St. George's. He also missed the cut in his only previous British Open appearance two years ago.

English started his second round at 3:43 p.m. local time Friday after beginning his first round five hours earlier on Thursday.

"It was nice this afternoon," said English, whose best British Open finish was a tie for 15th in 2013. "The wind was laying down. Very gettable pins out there. So I'm happy with the way I played, the way I hung in there. Could have easily given up after being 6 over, like you said, but got to stick with it. Just get the momentum going and anything can happen."

That's one reason Oosthuizen knows this tournament is far from finished.

This will be the fifth time in the past nine rounds at a major that Oosthuizen, the 2010 British Open champion at St. Andrews, has had at least a share of the lead. He was a runner-up at the past two majors, to Phil Mickelson at the the PGA Championship in May and to Jon Rahm the U.S. Open last month.

"I'm not really going to think about the second spots," Oosthuizen said when asked what he'll do differently this time. "I know my game is in a good place."

He'll also be aware of the quality of player behind him, though.

Morikawa, making quite a debut in major links golf, had seven birdies in his first 14 holes as part of a clinic in iron play. He missed a five-foot par putt on No. 15 — ending a 27-hole stretch without a bogey — and had a 10-foot birdie putt on the final hole catch the lip.

Spieth, four shots behind Morikawa when he teed off, was tied for the lead after 12 holes and then played the last six holes in 1 over, a stretch he described as "frustrating." The 2017 tournament winner at Royal Birkdale, he had plenty of looks at birdie on Friday, but the putts didn't drop like they did Thursday.

Then there was Johnson, a runner-up at Royal St. George's in 2011, who stuck his approach on the last hole to three feet for a birdie and a round of 65, which left him tied for fourth at 7 under with Scottie Scheffler (66) and South Africa's Dylan Frittelli (67).

The weather is expected to stay benign for the next two rounds, potentially favoring Johnson if the fairways firm up and the ball runs longer and faster.

"I like the position I'm in going into the weekend," Johnson said. "Still going to have to play some really good golf if I want to contend on Sunday."