It was nearly two decades ago, and its significance has grown with the benefit of hindsight.
The fight took place on December 6, 2004, and it was an important one - the final of the Torneo Italia, a prestigious multi-nations tournament.
In one corner was Jennifer Ogg from Canada, the reigning world lightweight champion, and a seasoned veteran at 33.
In the other corner was a teenage rookie from Ireland. Katie Taylor was just 18, nearly half the age of Ogg.
But all through that tournament, she'd kept talking about the Canadian.
Taylor didn't want to avoid her. She wanted to share a ring with the world champion, preferably in the final. She got her wish.
"She said I'm going to get to the final and box her. And she did,'' recalled her father and then coach, Pete.
"I mean by then Katie had had maybe five fights. Ogg had 250 fights. I remember ringing the National Stadium and saying she's fighting the world champion in the final. They said pull her out of it. She's only 18.
"I said she's comfortable fighting. She beat her by a mile on points. She was so determined."
That determination helped Katie to cut a swathe through the amateur game, winning five world titles, six European golds and Olympic gold.
That created a legacy. Hundreds of young girls were inspired by Taylor and laced up a pair of gloves. Future world champion Amy Broadhurst was one of them.
"It goes back to when I was eight years old. I asked my parents for a pair of Katie Taylor boxing boots for Christmas,'' said Broadhurst.
"They got me the same kind that she wore and I was thrilled. You can't copy another boxer, you need to focus on yourself, but I took inspiration from how Katie did things.
"To watch a woman dominate a sport to that extent...it's incredibly inspiring.
"It might sound strange but she boxes like a man. That's rare in women's boxing, I mean it as a compliment.
"In both the amateur and pro games, she's head and shoulders above nearly everyone. She's class."
To have a zero on her pro record bothers Taylor more than she'll let on. She certainly won't lack for motivation in Saturday's rematch with Chantelle Cameron in the 3Arena.
She will be counting down the seconds until both fighters get it on. Otherwise, fight week is a slog for the Irishwoman.
Taylor is in a sport where she wants to make waves and has to sell herself, but her instinct is to keep things low-key.
The split from her father and coach, Pete, was traumatic and sent her reeling. At one stage, she felt so lost that she'd sleep in her car in between training sessions with the Ireland team.
When Taylor returned from Rio seven years ago, she cut a haunted figure at Dublin Airport, and couldn't get out of the place quickly enough.
Only a couple of weeks later, we heard that she'd gone back to play soccer at Enniskerry FC in Wicklow.
Many figured it was just what she needed. Immerse herself in a team game again. Get out of the boxing bubble for a while.
But Taylor is ferociously competitive and ambitious.
Again and again, she talked of wanting to leave a legacy. She wanted double Olympic gold. She craved that sixth amateur world title.
And she found a new challenge to energise her in the pro game - something to reignite her fire in her 30s.
At 37, she should be in decline, and there are plenty who feel it's time to retire.
But Taylor maintains that she still has room for improvement, that she can get even better.
Such talk leads to scepticism but Team USA Head Coach Billy Walsh knows from his years in the Ireland set-up to never underestimate Taylor.
"That's the thing about Katie, she's put women's boxing on the map. Without Katie, it would be years behind where it is now,'' said Walsh.
"I keep coming back to this - Katie pushed women's boxing into the Olympics. Once they saw her, they saw the standard and knew they had to make the move.
"When I was with the Ireland team, I used to say this to the male boxers all the time - 'if you put in as much effort as Katie, we'd have far more gold medals'.
"It's hard to think of anyone from Ireland who's made such an impact on a global sport."
Just look at the list of the places where she won gold in the amateur game. All those lonely nights in outposts like Tonsberg, Katowice, Ningbo, Pazardzhik, Mykolaiv, Kezthely and Qinhuangdao - then fighting in front of acres of empty seats.
So a packed 3Arena roaring her own will always be special - and she can sometimes be carried along by the energy from the crowd.
"It's always great to fight in big venues in front of big crowds and I've been lucky enough to experience that,'' she said.
"But a lot of my amateur success came in strange venues around the world in front of small crowds. I probably do like to stand and fight a bit too much on occasion but I think that's just the fighter in me.
"Fans want to see the best taking on the best and as a boxer you want to be part of rivalries like this. These are the type of fights and nights that I was born for.
"When people watch me box, I hope they see a boxer, not a female boxer. I would love to bring the sport to another level and take women’s boxing to a place where people really respect it.”'
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