She was up to the task for the most part, especially going through holes seven to 12 on the most exposed part of the course in two-under par.
However, hole 13 was cruel. Ko drove into a fairway bunker, wedged out, lobbed to the back of the green, chipped on and three-putted for a triple bogey seven. Ouch.
That might have been the end for most 16-year-old amateurs on the Old Course; not Ko.
As is her custom, there was no palpable disappointment and she went on to birdie the last to give herself the best chance of playing the weekend.
She also recovered well playing off gravel on the 17th when her three-wood from 220 yards rolled four-feet past the pin, dipped off the green and tumbled down the hill.
The upside is Ko will have learnt plenty and, with similar conditions forecast tomorrow, the leaders might struggle to retain their places.
Ko acknowledged she was scrambling after hole 13.
"That was horrendous. I made a mistake [going in the bunker] but I should have finished with a bogey. I was pretty angry.
"The wind was tough especially down the last stretch. I was hitting a three-wood into the greens on 16 and 17 and I can't really expect to make pars doing that. I made some silly mistakes but a couple of birdies at the start would have helped my back nine."
Her coach, the Institute of Golf's Guy Wilson, says the result on 13 was exaggerated by one simple error.
"She had a bad shot off the tee, it wasn't so much how she hit it but the direction it went in."
He said the 17th was her next biggest challenge.
"That was an iconic shot to be playing in a British Open. Anyone from around here will know you do not go long. It was impossible to get up and down [in two shots].
"She was pretty bummed immediately afterwards not knowing whether it was good enough [to make the cut] but it is a huge testament to her game to make birdie on the last to give herself that chance."
