It's Friday the 13th, so apt that we can write the oddity and spook of the moment when we get to June and the fastest Australian woman of the season in the 100m freestyle becomes the first from her country to get inside 53sec.

Mollie O'Callaghan's victory in 52.87 on day 5 at Australian trials in Adelaide, en route to World titles in Singapore at the end of July, sets 2025 apart from all other seasons in the past decade - as the weakest on the clock going into a major international event when it comes to pace and numbers in the ranks of the Australian women's 100m free force.

Meg Harris, former training partner of O'Callaghan's, clocked 53.01 in heats before withdrawing from the final, her mission to race inside cut for relay consideration complete. Harris, who trains with Damien Jones at the Rackley Performance centre with Sam Short, Lily Price and squad made the shift in program when she moved back to Brisbane from South Australia (an earlier version of this article suggested Harris was still at St Peters Western - apologies).

The retirement of the Campbells, Cate and Bronte, Emma McKeon and Madi Wilson handed the chase for places on the Dolphins 4x100m team to the next wave, but that next wave took fairly hefty breaks after the Paris 2024 Olympic Games.

And so it is that we get to June 2025 with Dolphins leaping just under the radar on the women's 100m form guide, a first in a decade of dominance for Australia when it comes to pace and numbers. By that, I mean this, taking all seasons back to Tokyo 2021 and all seasons from 2015 to 2019, including one Olympic and two World long-course Championship seasons, we see the following pattern, the first number the count off women inside 53 in domestic waters heading into the major international of the year, the second number the count of swims by those women inside 53:

• 2024 - 4 - 10; 2023 - 3 - 7; 2022 - 3 - 3; 2021 - 4 - 15; 2019 - 3 - 7; 2018 - 2 - 3; 2017 - 2 -2; 2016 - 3 - 7.

Australia head coach Rohan Taylor said the Adelaide 2025 100m final “marked a changing of the guard", adding:

“This is the first year of four-year cycle with our eyes firmly on the LA Olympics. There’s experience with Mollie and Meg (Harris), Olivia Wunsch has a Games under her belt … tonight’s 100m is the start of a blueprint that will shape this event for LA.”

Best not make any prediction on the basis of any of that because, whether confirmed or not by any in the know, you can put your money on coach Boxall not having eased O'Callaghan into trials on the strength of a full taper.

On 53.12 in the 100m at the Open in April, St Peters Western ace O'Callaghan clocked 53.39 in heats, and then, in the final, was out third in 25.85, Carlile's Olivia Wunsch on 25.91, Alexandra Perkins first through in 25.80, and Hannah Casey 0.02sec away, Shayna Jack the last of the sub-26ers at the turn.

O'Callaghan, Olympic 200m, 4x100m, 4x200m freestyle champion and fourth in the 100m at Paris 2024, then did what she needed to do, a 27.02 confirming the squabble for the spoils top the 53-plus club. Wunsch grabbed the second ticket to Singapore, with Perkins, plus a snap for Casey and Abbey Webb, guaranteed places on the relay at Worlds. Teenagers Milla Jansen and Jaimie De Lutiis were the last home inside 54, leaving Jack locked out of all 100 chances, on 54.03.

Swimming Australia looked at the positive in the mix: all eight finalist got inside the cut time for Singapore. Fine - but hardly a line that speaks to Dolphin standards.

O'Callaghan's win secured her a fourth solo swim in Singapore after second-place finishes in the 50m back, 100m back and victory in the 200m free. Speaking through Swimming Australia, she said:

“Dean (Boxall) has spoken to me about this prep, that it’s not about time, it’s just about racing. I think I’ve learned so much, probably mentally this time, not so much physically … and it’s just about racing and enjoying it. I think in the long run, I’ve learnt so much about myself, and I wouldn’t change a thing.”

The word 'fun' pops up a lot. What does it mean? Says O'Callaghan:

“It’s the friendships, it’s getting to travel, getting to do what my dreams are, getting the opportunity to go around the world, to see new things. So I think fun at the end of the day is hopping in the pool, knowing that I gave it my all and got the best out of myself… as I said before, bad experiences make the best experience better.”

Wunsch's take:

“I’ve always loved swimming, I love racing, so that’s why I train. So I’m really excited to be back on deck. We really didn’t know where I was going to be.. coming off glandular (fever) so just really excited to be back with a lot more to work on. I think it’s more satisfying to touch second. I mean the time is nice, but I know there’s a lot more to work on and a lot more I can do. A little bit of fine tuning into Worlds and I’m really excited to be on the team off the back of the Olympics. I had a lot of fun tonight with the girls and it’s always such a privilege to race with them.”

• RESULTS IN FULL

What does that all mean for Australia's bull run in the women's 4x100m free relay? Who can say when one side must be practically at their best to make the grade, and one side with its star turns not taking the same approach this season.

On paper, here the AUS Vs USA 4x100 approach to Singapore on season speed: