That required text updates from former men's world number one, Englishman Justin Rose, who he worked with for 11 years, before splitting in June 2020.
"When you're driving for six hours, you kind of just blank out, and so I checked the score and saw that she was four-under thru four, and so I texted Rosie a screenshot and just said 'I guess you never know.'" Foley told the Herald.
"And then what felt like 10 minutes but was like two hours later, he texted me that she was something like eight-under thru 10."
He pauses.
"I don't remember, but it was some number that didn't make sense in your brain."
That's exactly what it was as Ko's round left Foley utterly gobsmacked.
The American's worked with some of the biggest names in men's golf – Tiger Woods being the most high-profile - and been part of their journeys as they dominated fairways and greens the world over. But that's still led him to calling Ko's performance "Probably one of the great rounds of major championships."
Foley admits that the 23-year-old's success last decade, winning two majors and having 15 LPGA Tour victories, may have inspired the likes of Tavatanakit.
"Patty's what, 21? So she was in high school when Lydia was number one in the world. So that's the thing, the generation after greatness, they see that as possible."
Ko mentioned after the tournament how a last-minute pep talk from Foley led to her astounding final round.
"I was warming up before the round when my phone rang. I thought it was highly likely a scam call ... but it was Sean, on his way to the Masters [starting at Augusta National later this week]," Ko said.
"He told me no lead is ever too far away and told me to go out there and play my own game, that I play with 100 per cent conviction. Sean is like that. He'd often give me a word slap, like a wakeup and we all need that sometimes. Sometimes I get in the way of myself ... it's me against the golf course and he reminds me that 'me' is the hardest part to get over."
Foley's pulled the curtain to explain what their conversations tend to be made up of.
"We have a couple of key words like 'trust your training' and 'believe in your intelligence instead of your intellect', just little things that you keep bringing up and bringing up. Last week and earlier this week she was being a bit judgemental of her game, and I just said 'look, you've been working hard, and at the end of the day, take last week [tied for 26th at the Kia Classic] out of it, you're a human being, and golf's hard. But the last eight events you've averaged sixth place, so just be confident of where you're at."
While wanting to emphasise it isn't a breakthrough result for Ko, nor is it a reminder to herself of how good she is, Foley believes it's clear that she is enjoying her golf more now.
"She might not have won the tournament, but she won.
"Some players need to beat the field, and some players need to be themselves, and it's probably suffocating to be number one in the world at anything when you're 17. At 17, I was just happy to jump out of my bedroom window and not get caught. Just think about what you were doing at 17, what anyone was doing at 17.
"It's [being world number one] a great gift but it's a curse too, and she went through the tough times, but that's probably what's needed to go on to greatness… I think she probably appreciates it more now, but who wouldn't want to play golf after watching her play this week? If she's shooting 62 or 68 or 71, who smiles more on the course than that?"
