On a day to remember for the West Kilbride player, she carded a four-under-par 68, matching the effort of 2018 winner Georgia Hall in the same group and finding herself just one shot off the lead after the opening circuit.
It was a sensational start for Duncan, who earned her place in the field for the season’s final major by winning the R&A Women’s Amateur Championship at Kilmarnock (Barassie) earlier in June and, on both that and this evidence, looks a star in the making.
“Emotions were very nervous with a wee bit of excitement in there,” said a smiling Duncan after receiving one of the loudest cheers of the day on the 18th green.
“And then when it started to go really well the nerves came back, heart rate went up. But, overall, really enjoyed it, and I'm already looking forward to tomorrow.”
Duncan had played with 2009 winner Catriona Matthew, defending champion Sophia Popov and the ever-improving Leona Maguire in one of her practice rounds earlier in the week.
That definitely helped, as did the fact her caddie this week is Dean Robertson, a former European Tour winner who constantly helps Stirling University, where Duncan is currently part of the programme, churn out top players.
Starting with a birdie always helps, especially when you are venturing into new territory, and Duncan made another gain at the sixth before dropping shots at the seventh and 11th.
Her day was then transformed by a birdie-birdie-50-foot eagle burst before showing both class and maturity by covering Carnoustie’s fearsome closing four holes in level-par. “Yeah, that was huge,” she admitted. “I felt it was actually bigger than the wee stretch of birdies and eagle.”
Duncan will be up bright and early for her second circuit and admitted: “It's definitely a good thing. Obviously means that I don't have to hang around in the morning. I can just get up and go and get finished.”
In contrast to Duncan, Kylie Henry is making her ninth appearance in this event, having made her debut at the same venue in 2011. “So this has got a wee special place in my heart,” she admitted after also ending up in red figures with an opening 71.
“Every time you still get the real buzz and excitement and a real special feeling on the first tee. It's almost quite emotional, actually. It's great.”
In what she admitted had been an “adventurous” round, Henry started and finished with back-to-back bogeys but had five birdies as she produced some “good stuff” in between.“I think that's as easy as we'll get it,” said the 34-year-old Glaswegian of the unusually benign conditions at the Angus venue. “Obviously, the rough was a bit damp, so as soon as you were in the rough, it was hard, even if the lie looked good.
“Like on the last there, I hit it down the left rough, but the lie was great and that sucked me into trying to hit a 6-iron, which was so stupid.”
This week’s prize pot of $5.8 million is the biggest in the history of the women’s game, with another $1m set to be added for next year’s first visit to Muirfield.“I think the R&A and AIG have done amazing for us,” said Henry of that huge boost. ”It's not even so much about the money. It's actually, like you say, giving us the credit we deserve.
“We've always been made to feel like we're lesser than the men, but when you get big boosts like that, it makes you feel great, and it makes you feel like this is where you want to be playing."
Earlier in the day, Kelsey MacDonald said it had been an “absolute honour” to hit the opening tee shot on her debut in the event but then didn’t enjoy having to “run round”.
The Scot’s group was put on the clock as early as the fourth hole following their 6.30am start, with the rules official staying with them for the remainder of the round.
MacDonald, who is one of the quicker players in the women’s game, didn’t reveal the identity of the person causing the concern about slow play on the opening morning at the Angus venue.
“It wasn’t me, that’s all I am saying,” said the 30-year-old Nairn woman, who was in a group along with American Sarah Schmelzel and Chloe Williams of Wales.
However, finding herself in that awful position definitely contributed to MacDonald, who had been two-under after six and still going along nicely at the turn, having to settle for a three-over 75.
“We were put on the clock from the fourth hole, so it was not ideal,” said the first of five Scots to step into action in the $5.8 million event.
“Unfortunately, it was one of those things, but it felt like I was having to run round and it’s not really what you want in your first experience of the Women’s Open.
“It’s not nice when you have a referee following you the whole way round. I did find that quite hard.
“I’m a fairly quick player. You have to try and forget about that but, when your whole group is being monitored and you have just one shot you take a bit longer over, then you are going to be penalised and that’s a tough one.”
Gemma Dryburgh, the top-ranked Scot, had to settle for a 76, two less than Matthew, who dropped four shots over that tough closing stretch as she came home in 40.