Oosthuizen fired an eagle and four birdies as he added a 65 to his opening 64 for a total of 129.
Louis Oosthuizen will take a two-shot lead into the third round of the 149th Open after recording the lowest halfway total in championship history at Royal St George’s.
Oosthuizen fired an eagle and four birdies as he added a 65 to his opening 64 for a total of 129, eclipsing the previous best of 130 set by Sir Nick Faldo in 1992 and matched by Brandt Snedeker in 2012.
“I only heard that when I walked in,” Oosthuizen said. “I was not aware of what it was but to have any record at the Open is always very special.”
Only a bogey on the 16th prevented Oosthuizen from matching the lowest halfway score in any major – Brooks Koepka’s 128 in the 2019 US PGA – but he will be more concerned with the Claret Jug than records after the events of this season.
Already a runner-up in all four major championships, Oosthuizen took his unwanted total of near misses to six by finishing second in both the US PGA at Kiawah Island and the US Open at Torrey Pines.
“It’s more inspiration (than frustration) that I can still compete in majors,” said the 38-year-old South African, who won the Open at St Andrews in 2010 and lost a play-off at the same venue in 2015. “I just need to pull it through and see if I can go one better.”
Morikawa had earlier been blissfully unaware of his own chance to make history, seven birdies in the first 14 holes meaning he needed to play the remaining four in two under to card the lowest round in any men’s major.
However, Morikawa bogeyed the 15th and missed good birdie chances on the 16th and 18th to return a 64, a shot outside the course record and two adrift of the major mark set by Branden Grace at Royal Birkdale in 2017.
Morikawa’s halfway total of 131 was also a shot outside the Open record which Oosthuizen would later break, but he said: “I had no clue what any record was. I’m awful with that stuff. I know now.”
Morikawa could only finish in a tie for 71st in last week’s Scottish Open but credited the experience – and changing three of his irons to cope with the links turf – for his performance at Royal St George’s, where Ben Curtis was the last debutant to win the Open in 2003.
The biggest difference is that Curtis was 396th in the world at the time, while Morikawa is ranked fourth and already a major champion following his victory at Harding Park last August.
“Last week I wanted to win but I came out of it learning a lot more,” Morikawa said. “The style of golf is different and last week helped tremendously.
“I would not be here if I had not played last week. Just having fescue fairways where the ball sits differently was huge to see. I changed some of my irons strictly because I could not find the centre of the clubface.”
Spieth felt he let a great round slip away after carding five birdies and two bogeys in his 67, adding: “Today was a day that could have been a really special one.
“I felt like I had a really low one in me. I’m in a great position but have kind of a bad taste in my mouth with what could have been.”
World number one Dustin Johnson is four shots off the lead after a second round of 65, with Andy Sullivan leading the English challenge on six under and compatriot Paul Casey a shot further back alongside four-time major winner Brooks Koepka and US Open champion Jon Rahm.
Defending champion Shane Lowry is four under after a superb 65, with Rory McIlroy level par and Bryson DeChambeau making the cut on the mark of one over.