Mostert, however, was quick to acknowledge he was favoured by being able to play the majority of his round in the morning.
The morning field, who marked the return of professional golf in South Africa with the first tournament of the Sunshine Tour’s Rise Up Series, were greeted by brutal conditions – freezing temperatures and a four-club wind that combined to make the greens play like ice-rinks.
Level-par was the best score anyone in the morning field could manage.
Come the afternoon, the sun began shining more brightly and the wind died down.
Not that Killarney was playing easy then either, and Mostert’s three-under-par 67 was the best score of the day, one better than the 68s shot by Dylan Naidoo, Ruan Korb and Albert Venter.
Michael Hollick, Wallie Coetsee, Makhetha Mazibuko and Anton Haig were on one-under, while seasoned Sunshine Tour pros such as Keith Horne, Jaco Ahlers, Adilson da Silva, Danie van Tonder and Ulrich van den Berg were among the golfers who finished on level-par.
“I hit a lot of greens because as soon as you are far away from the holes here you don’t have much chance,” Mostert said after his round.
“And I only hit three or four drivers. I used my irons to plot my way around.
“I have game-plans for both winds and if it blows the opposite away tomorrow I can probably use more drivers, but you have to be really careful where you leave the ball as you have to be on the right side of the greens.
“And it was a helluva lot easier in the afternoon. I heard it was very cold in the morning and the greens were probably a lot firmer.
“It was a bit windy all day, but no more than a two-club wind this afternoon, so nothing overly bad, but it must have been really hard to stop the ball on the greens this morning.
“It will be a lot colder tomorrow when I play, so I’m going to have to grind it out.”
Venter had a share of the lead until a bogey at the ninth hole – his last – when he missed the green on the left and was left with no shot for par. But considering that it was the 24-year-old’s first ever Sunshine Tour round, it was a top-class effort.
He started on the 10th and made par and then immediately dispelled any nerves with a tremendous run of four successive birdies.
“For my first event I’m really happy with my day’s work because I had quite a few nerves,” Venter said.
“But I had a brilliant start, a really good tee-shot down 10 and then on 11 I holed my shot from the greenside bunker, so that was a real boost of confidence.
“I just hit the ball well, got it close to the hole and made good putts. It was just a matter of planning every shot.”