Oosthuizen already has his name on the Claret Jug after his victory at St Andrews in 2010 but he is also the member of a less popular Major Championship club having finished second at all four of golf's biggest events.
He has six runner-up finishes in total, including two on the 2021 Race to Dubai, but he is clearly showing no ill effects and has recorded just a single bogey so far in a stunning display on the English coast.
“I only heard that when I walked in,” Oosthuizen said of the halfway record. “I was not aware of what it was but to have any record at The Open is always very special.
“I think I have really played good the last two days and today we got lucky the last nine holes. It was as good weather as you can get playing this course and all of us took advantage.
"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 any opportunities for birdies.
"Around this golf course, a lot of things can happen. I don't think you want to think too much of it on a links course until you get to that 18th green and hopefully you have a lead."
Oosthuizen made the perfect start with a birdie from four feet after playing the first in textbook fashion and he took advantage of the par five seventh as he got up and down.
To have any record at The Open is always very special
A tap-in at the 12th had him alongside early pacesetter Morikawa and another birdie from 15 feet on the 13th sent the 38-year-old into double figures.
But better was to come as he put his second on the par five next to 25 feet and rolled home the eagle putt to lead by three.
A poor tee shot on the par three 16th led to a first bogey of the week but there is no doubt who has been the headline act over the first two days.
Morikawa started the day three shots off the lead but soon set about reeling Oosthuizen in and hit the front as he turned in 31 courtesy of a long putt on the eighth and approaches inside six feet on the first, fifth and ninth.
The 2020 US PGA Championship winner had the wind in his sails and when he added a 12 footer at the 11th to two more remarkable irons into the 12th and 14th, he was four ahead and on track for a course record.
A dropped shot on the next stalled his momentum but he still had a six footer at the 18th for a 63, missing to set the target at nine under.
Spieth carded a 67, a score matched by Frittelli, while Johnson made six birdies in ten holes either side of the turn but also made two bogeys before picking up a shot on the last in his 65.
Scheffler recovered from an early bogey with five birdies in a 66 to sit a shot ahead of South African duo Justin Harding and Daniel van Tonder, German Marcel Siem, leading home hope Andy Sullivan and Argentina's Emiliano Grillo, who matched Morikawa's 64.
Race to Dubai Rankings Presented by Rolex leader Jon Rahm also carded a 64 to sit at five under alongside England's Paul Casey, Americans Brooks Koepka and Cameron Tringale, and Canadian Mackenzie Hughes.