It is a question thousands of golf fans are sure to be asking this week as they pack Royal Portrush for the first Irish Open in Northern Ireland since 1953.
How on earth did Rory McIlroy shoot 61 around this place?
Even more amazingly, how on earth did he do it when he was just 16 years old?
Seven years on McIlroy is back as world number two and as a major winner as well, but he is also desperate to hit back from four missed cuts in his last five starts.
Although the last of those was his US Open title defence just two weeks ago, the Holywood star sounds upbeat as he approaches what is bound to be a memorable few days for all those concerned with the event’s return north.
“The first ever European Tour event to sell out is something that’s obviously got a lot of people very excited and it’s shaping up to be a great week,” he said.
“I’ve put 10 days of really good work in. My game feels good – it actually felt pretty good at the US Open.
“It’s just that if you are slightly off at a US Open it’s so hard to get yourself into contention.
“In a way it couldn’t be a better time to come back here and play Portrush. It brings back so many good memories and you can feed off that.”
The main memory, of course, is that 61.
“I can basically remember every shot. I remember I missed a six-footer on the first for birdie – it could have been better!
“It was just one of those days where everything is on song. I turned three under, eagled 10, birdied 11, parred 12 and 13 and then birdied my way in.
“I’ve only had it a few times. People call it ‘in the zone’ – I got to six under and wanted to get to seven under, then I wanted to get to eight under.” He finished 11 under.
“Seven years ago – time goes pretty quickly.”
And what a seven years for Irish golf. Dubliner Padraig Harrington achieved back-to-back Open Championship and back-to-back major wins in 2007 and 2008, then came Graeme McDowell’s US Open victory two years ago – the first by any European since 1970.
Twelve months later McIlroy kept that trophy in Northern Irish hands and a month after that 42-year-old Darren Clarke won the Open at Sandwich.
“I think it’s just been a knock-on effect. It all started back with Padraig, what G-Mac did really inspired me and then Darren sees us – me especially, being the little 12-year-old that he took down as part of his foundation in Portmarnock.
“He’s probably thinking ‘if that little squirt can do it, so can I’.”
The course has been set up this week nearly 300 yards longer than when McIlroy posted his 61.
“I’d take four 69s and see what happens I think.”
He is trying a different attitude to previous Irish Opens – with good reason given his three most recent finishes in it were 34th, 35th and 50th.
“To be honest, the last couple of years I didn’t quite enjoy the tag of home favourite. I just didn’t feel very comfortable with it.
“This year I really want to embrace that. You look at so many people and when they’ve got a home advantage it is an advantage.
“It should be for not just me, but for the guys from here.”
This is McIlroy’s last event before the Open at Royal Lytham. He left Sandwich last year – after a 25th place finish – doubting his ability ever to conquer bad weather.
The coming week and month could well be another test of that, but he states: “I want to try to become a better wind and bad weather player and the only way to do that is by playing in it.
“I got back home at the weekend and the weather was not particularly good, but I dragged myself out and hit balls and was like ‘this could actually be very beneficial for me’.”
There was also the admission after an early exit from Wentworth that he had “maybe taken my eye off the ball a little bit” and he has also faced accusations that perhaps he does not dig in as deep as he should when things are not working out as he hoped.
“Definitely in the past if things haven’t gone my way the fight goes out of me pretty quickly. That’s something I’m working on and something that I’m trying to get better at.”