Florian Wellbrock and Axel Reymond both won gold as a successful open water campaign concluded in Yeosu, South Korea.
While Wellbrock stood on the top step of the 10km podium, Reymond triumphed in the 25km, the final event held in rainy, challenging conditions.
Gregorio Paltrinieri – who Welbrock will face in the distance freestyle events in the pool – moved a step closer to making history after he was part of the Italy team that won silver in the 5km event.
If, as expected, the Olympic 1500m freestyle champion wins a medal in the pool, he will become the first man to win to stand on the podium in both the open water and pool at the same World Championships.
Wellbrock hit the touchpad just 0.2 secs ahead of fellow arena swimmer Marc-Antoine Olivier as the pair took gold and silver as well as securing Olympic qualification in the men’s 10km.
Wellbrock, of Germany, has emerged over the last 12 months as a real force in both pool and open water and he beat Olivier in a sprint finish over the final 200m in 1hr 47mins 55.90secs.
Paltrinieri was sixth (1:48:01.00), one place ahead of Ferry Weertman (1:48:01.90) who ensured he will attempt to defend his Olympic title in Tokyo next year.
The 21-year-old Wellbrock led for much of the race, apart from a brief spell when he dropped to sixth to save energy, the German claiming there had been no race strategy but instead to go out and win.
He said: “I love competing in open water swimming and I tried to be the best.
“I know that it’s a big and also a hard step to be on the podium next year in Tokyo but with hard work it may be possible. I expect to race in the pool events in Tokyo the week before the marathon 10km.”
Olivier, who is making his first trip to Asia, feels close to nature when he is competing in open water although he had slightly mixed feelings, his satisfaction tempered by being blocked at the finish of what was a battle royale.
He said: “I tried to put my tactics in place but it was really very difficult. The qualifying year for the Olympics, people fight for a spot.”
Reymond successfully defended his 2017 title in 4:51.06 and said: “It was a hard race and a hard competition but we love it.
“In the early part of the race, Marco (Marc-Antoine Olivier) was with me and we tried several times to get ahead of the group. It didn’t work and we both had trouble staying on a fixed trajectory.
“The last 400m was very, very tough and it was the hardest finish of my life. I thought that the title was going to be really hard.
“I was able to breathe and I made a touch. I don’t even know how I did it.”
There was a double celebration for Haley Anderson when her hard-fought silver medal in the women’s 10km also earned her a slot on the United States team for Tokyo 2020.
While Haley respects the sea and finds calm within it, she described the race as “brutal and cut-throat” as the field of 64 fought for the top 10 places that secured a berth for Tokyo.
She finished just 0.9secs off gold in 1:54:48.10 as Sharon van Rouwendaal claimed the 10th and final qualifying spot to ensure she will defend her Olympic title.
But her joy was Aurelie Muller’s pain as the 2017 champion was locked out by one place and 0.10secs in 11th.
Anderson’s medal is the first for the United States in the 10km and complements her two 5km titles from 2013 and 2015.
The 27-year-old won silver at the 2012 Olympics in London before coming fifth in Rio de Janeiro and she said: “I’m so excited. I can’t believe it. Not just making my third Olympics but finally medalling in the 10k at worlds is really exciting. I’m just so stoked for next year.”
Muller returned the following day to take second in the 5km in 57:57 but she hinted at retirement.
She said: “I’m second and I’m thinking why I’m not going to swim in the Olympics.
“I’m proud of myself. I figured maybe this would be my last race and I’d like to end up on something good, something positive. If it was my last race, I did it well.”
Logan Fontaine won silver in the men’s 5km in the opening race of the open water programme in 53:32.20.
It was Logan’s second world medal after he was part of the French 5km team that won gold at Lake Balaton, Budapest, in 2017.