Day 1 in summary, full links below: Summer McIntosh, of Canada, made it one gold down, four targets to go when she became the fray Canadian ever to claim the women's 400m freestyle world title.

Only the G.O.A.T, Michael Phelps, has ever won five individual gold medals at the global long-course showcase (or, indeed, the Olympic Games). Sarah Sjöström, the Swedish sprint queen out of acton this year for the best of reasons - baby on the way - holds the record for most solo medals at one World Championships, five, from Gwangju 2019.

Just over 20 minutes after victory, McIntosh booked a ticket to lane 4 for the 200m medley final on day 2.

The men's 400m freestyle witnessed a rollercoaster of a men's 400m freestyle final that ended in victory by 0.02sec for Olympic champion Lukas Märtens over Australia's Sam Short. Kim Woomin, of Korea, was fight there with them, his bronze followed by a 3:44 Swedish record from Victor Johansson, the man who last year confined Anders Holmertz's 1992 Olympic-bronze-medal time from the 1992 Games in Barcelona to history on the national record books. Great swim for Johansson, one that reminds us just how good Holmertz was more than three decades ago, finishing adrift a young Kieren Perkins, who was adrift the Unified Team's Evgeny Sadovyi.

And then came the 4x100m free relays - gold for Australia in both, the results laced with the drain of gastroenteritis that sadly inflicted a number of USA swimmers on their prep camp in Thailand, but stacked, too, with the tactics and times required for Dolphin victory.

The debrief of the U.S. team will surely be asking questions about details of the plan that may have contributed to the issue that is clearly having an impact in the team so far here in Singapore. Great Britain was at the same venue but was housed in a separate part of the resort, while the U.S. was in the public part of the well-regarded luxury sports and wellness facility in Thailand that is often frequented by international sports teams, among them many swim squads from all over the world. The Brits had a few stomach issues too, and while anyone can be 'unlucky', there's not much room to leave things to luck in sport.

Medals Table After Day 1:

The records:

Men's 400m Freestyle
Victor Johansson - Sweden - 3:45.26 - National record
Victor Johansson - Sweden - 3:44.68 - National record

Women's 400m freestyle
Li Bingjie. - China - 3:58.21 - Asian and National record
Neats:
Gan Ching Hwee - Singapore - 4:09.81 - National record
Kyra Rabess - Cayman Islands - 4:23.08 - National record

Men's 4×100 freestyle
Australia: Flynn Southam; Kai Taylor; Maximillian Giuliani; Kyle Chalmers 3:08.97 - Championship, Commonwealth, Oceania and Australia
Italy: Carlos D'Ambrosio; Thomas Ceccon; Lorenzo Zazzeri; Manuel Frigo; Leonardo Deplano 3:09.58 - Italian record
Other national records: Israel and Lithuania

Women's 4x100m Freestyle
No national quartets set records (neutral teams cannot set national records in international waters if they are not representing a naton, and that is logically the case, even though it has been indicated elsewhere that neutrals can hold team records, their national identity guaranteeing that they cannot be meaningfully regarded as being neutral.

The Action:

Summer's Double Trouble For The Rest

W400 Free: McIntosh Sets Sail On Trail Of Golden High-Five Haul With Cool Victory In 400 Free

“I think tonight is my biggest night of the whole meet. So to come out with a gold medal and a really good, strong semi-final in the 200IM, I’m really happy.” Canadian ace Summer McIntosh, one golden target down, four to go

State Of Swimming +Craig Lord

When 0.02 Split Lukas & Sam

M400Free: Märtens Adds World To Olympic Crown In Epic Battle With Short

“There was a lot of pressure. Also as a world record holder, it was not easy to fight these guys. But I tried my best, I gave out everything, and I’m really happy and proud to be a world champion. Now, Germany has a new world champion, and that’s not usual I think. Really proud.” - Lukas Märtens

State Of Swimming +Craig Lord

Aussie Relay Riot:

End Of Dolphins’ Golden Sprint Relay Run? No Chance, Shout O’Callaghan, Harris, Jansen & Wunsch

“I think it’s amazing, we have a pretty rookie-dominated team at the moment, so it’s nice to see the younger swimmers lift up ... it’s great to see (the new athletes) getting the experience and putting down so much effort and determination into this meet.” Mollie O’Callaghan

State Of Swimming +Craig Lord

Dolphin Damage: Four-Records 3:08.9 Victory For Southam, Taylor, Giuliani & Sprint-Orca Chalmers

“The boys set me up and made my job very easy tonight. I’m just desperate every single time, I race to win. I love nothing more than a dog fight in that last 50 and getting a hand on the wall first” - Kyle Chalmers

State Of Swimming +Craig Lord

Nicolo In, Out, Shaken All About - & Back In, To A 9-Lane Final

Day 1 Semis: Martinenghi In, Out, Shake It All About In A 9-Lane Final

No the Italian who moved on the blocks. Ok, so who did? No answer. A shrug. Perhaps no-one did. Perhaps someone did but it was deemed unfair, given that officials had made their own mistake and they’d be no penalty. We may never know…

State Of Swimming +Craig Lord