The last session of the last day of the China Open in Shenzhen started with a men's 50m butterfly final in which the medals were split by 0.04 and the top 4 by 0.08, but the eye was drawn to a different moment of dashing speed as the meet came to a close:

The men's 800m freestyle final delivered a third career best and third victory for Zhang Zhanshuo over Lukas Märtens, 7:44.45 to 7:46.97 in the 800m freestyle.

So much for that. But what about this:

• Last 50m: 24.95
• Last 100m: 53.45

Those two splits are the fastest ever seen at the end of an 800m free that ended in a swim under 7:45. That means, faster than:

• 2009: Zhang Lin's World record closer of 54.09 - 28.10, 25.99 - an off-the-chart swim that remains the fastest finish ever
• 2011: Sun Yang* world title (2nd fastest finish ever): 54.48 - 27.61 - 26.87
• 2021: Bobby Finke's gold rush at Tokyo2021: 26.39 his winner of a last lap
• 2023: Ahmed Hafnaoui** world title - 54.84 - 28.60; 26.24
• 2024: Daniel Wiffen fending off Finke at Paris 2024 - 54.86 - 28.39; 26.47
• 2025: Ahmed Jaouadi & his world title win - 55.50 - 28.28; 27.22
• * two WADA-Code violations, banned for 4 years, three months for second offence. Competed domestically again for first time in 2025 but is barred from selection to the China team
• ** - suspended for 21 months due to three missed doping tests within a 12-month period. The ban ended on 10 January 2026.

So, 2026, March, the China Open - Zhang Zhanshuo - 53.45 - 28.50 - 24.95

As said, the third career high of the week for Zhang, 18 going on 19, and the third time he'd kept Märtens at bay: 200m, then 400m, and today 800m.

Here's how the last of their clashes went before Zhang celebrated a best time of 7:44.45, inside the 7:46:69 he clocked at the 15th National Games last November.

Here's how it flowed for Zhang and Märtens today in Shenzhen:

• 55.67; 1:55.23; 2;54.70; 3:54.07; 4:53. 28; 5:52.96; 6:51.00; 7:44.45 (53.45, 28.50 - 24.95) Zhang
• 55.29; 1:54.77; 2:54.25; 3:53.96; 4:53.17; 5:52.36; 6:51.11; 7:46.97 (55.86, 28.52 27.34) Märtens

Good swim for the World-Championship bronze medallist of Singapore 2025, Olympic and World Champion and World record holder and the first and only man under 3:40 over 400m. Practically a stroke-for-stroke the whole way, until the German ace found himself next to a teenager capable of closing a sub-7:44 800m free 2.39sec faster than him.

In a blistering 800m world-title final last year in Singapore, the podium placers, tapered and in the championship form of their lives, finished with these splits:

• 28.28 - 27.22 Ahmed Jaouadi (TUN)
• 29.03 - 27.18 Sven Schwartz (GER)
• 28.83 - 27.18 Lukas Märtens (GER)

The one Chinese swimmer, Fei Liwei, finished 11th, in 7:51.01, his last two laps a 29.65 and 27.65.

The only two Chinese swimmers to have raced inside 78:40: world-record holder Zhang Lin, his otherworldly 7:32.12 from a time of shiny suits and other doubts in 2009 as solid and strange as it ever was; and Sun Yang*, who at the same global titles in Rome took bronze in the 1500m freestyle ahead 17. 2009. That's also the year the man third home today was born. Li Chengyu is 16, going on 17 - and already under 8mins.

Make of all that what you will.

Meanwhile, here are the numbers of swimmers 17 and under and 15 and under who raced into and in finals at the China Open this week:

Below, a complete day-by-day breakdown of all those swimmers and where they finished at the open + In other action on Day 4, including...

• RESULTS IN FULL (Chinese names in Chinese on official results - all finals listed in full in English below).