Louis Oosthuizen did not realise he had broken an Open Championship record until he got off the course at Royal St George's on Friday.

The South African carded a 65 to move to 11 under, with his overall score of 129 the lowest after 36 holes at golf's oldest major.

It left the 2010 Champion Golfer of the Year two strokes clear of Collin Morikawa, with Jordan Spieth one stroke further back.

But Oosthuizen, who has finished second in two majors already this year, had no idea he had just made history when he sunk a par putt at the last.

"I only heard that when I walked in, so I wasn't aware of what it even was before," he conceded after fine conditions made the Kent links ripe for low scoring, with playing partners Jon Rahm and Shane Lowry shooting 64 and 65 respectively.

"To have any record at the Open or part of any record at the Open is always very special.

"I think I've played really good the last two days. It was as good a weather as you can get playing this golf course. All of us took advantage of that.

"I think in our three-ball we had a 64 and two 65s, which you don't really see around a links golf course."

The 38-year-old has had a succession of close calls since he claimed the Claret Jug at St Andrews 11 years ago, with a remarkable six runner-up spots in majors.

Asked if there was an issue with getting it over the line, he replied: "I don't know. I think in a few of them I needed to play just that little bit better coming down the stretch.

"It's just I don't think I would have done a lot different in a lot of them.

"Right now I think where my game is at, I just need to put myself in position, and this year is the best I've been putting, and I just need to hit greens and give myself opportunities for birdies."