Jake Wightman said his world 1500m silver medal felt like gold after making his return to a global podium, but British team-mate Josh Kerr's title defence was ruined by a calf injury in a dramatic final in Tokyo.
Wightman, the 2022 world champion, achieved redemption having struggled with injuries and missed the past two major championships.
The 31-year-old collapsed with exhaustion after crossing the line before staring up at the big screen, which revealed Portugal's Isaac Nader had pipped him to gold by two hundredths of a second in a thrilling finish.
Although he came up agonisingly short, it is a second place which he said felt as good as first after the challenges of recent years - and Britain's long-awaited first medal of the championships.
"It will take a while to process this. I'm a big believer that you get what you put in at some point. I'm just very, very happy that all the persistence has been well worth it," Wightman told BBC Sport.
"I felt like I had another gear through the rounds. All I'd said was that I would hit the front at some point. I did not know what would happen and I nearly got there.
"For me this is a gold. Just getting on the start line at a championship final is a gold.
"I went into it with a bit of freedom that whatever would happen, happens."
'It's been a bleak couple of years, this is like a gold to me' - Wightman on 1500m silver
However, there was heartbreak for Kerr, seeking to become only the fourth man to retain the 1500m title but denied the opportunity after pulling up in pain on the penultimate lap.
Having positioned himself at the back of the race from the start, he eventually managed to hobble over the line and finished last. Neil Gourley was 10th.
Great Britain have had to wait until the fifth day of competition to celebrate success in Japan, where they were set a target of a top-eight finish following a record-equalling haul of 10 medals in 2023.
But Wightman's stunning silver lifted them to 17th in the medal table.
Former Olympic long jump champion Greg Rutherford said on BBC TV: "Everybody suffers with injuries in their careers. Jake Wightman shows that you can come back from it and the good guys do still win medals.
"For anybody young watching this, suffering with something difficult, it shows that you can push through."
Calf injury hinders Kerr in world title defence
World Athletics medal table - and what's on Thursday?
World Athletics: Recap as Wightman wins silver and Kerr injured in 1500m final
Wightman has endured a long road to return to the position of fighting for the sport's biggest prizes, since his crowning moment three years ago.
But he has always maintained his belief that he would get there.
Wightman was accepting that the injury which kept him out of Budapest two years ago was a consequence of the demands of winning world, European and Commonwealth medals in an intense 33-day period in 2022.
But his hopes of returning to the global stage at last summer's Olympics were cruelly ended by a hamstring tear just one week out.
By that point, he had already been wearing the team's kit at their final training camp in St Moritz.
Geoff Wightman reacts to son Jake winning World Athletics Championships silver
Wightman sought a refresh this year, making the difficult decision to end his coaching partnership with father Geoff, who was commentating inside the stadium when his son outlasted Jakob Ingebrigtsen to win gold in Eugene.
In what has been a year of significant change away from the track, Wightman began working with his partner Georgie's father, John Hartigan, and relocated to Manchester to be closer to his physiotherapist.
The only major change in terms of his training, Wightman says, has been to respect his body more.
"Honestly, it has been a very, very bleak couple of years for me. A lot of times I doubted if could make it back to this level," Wightman said.
"I have made some huge changes in my life this year. I want to thank my coaching team and my dad for getting me to this point in the first place. He did all the hard work bringing me to this level."
He added: "When you get that close you cannot help but think 'what if I had tried a bit more?' But I left everything out there."
Once again commentating at the stadium where his son celebrated his medal, his father Geoff told BBC Sport: "Jake could not have given any more there, it was pretty much a perfect race from him. I'm very proud.
"He dipped, which he does not usually do. I have given him a hard time for that sometimes. I hope I have contributed to that as well.
"[His mum] Susan and I are just very proud and we are enjoying the moment with him. I will be calling his medal ceremony tomorrow, so I will need to have a stiff upper lip for that."
'There was something amiss' Cram and Radcliffe anlayse what went wrong for Kerr
After a slow start to the championships, Great Britain's medal hopes were dented by an early 400m exit for the out-of-sorts Matthew Hudson-Smith on Tuesday.
GB missed out on a mixed 4x400m relay medal on the opening night, Emile Cairess succumbed to the searing heat in the men's marathon and Molly Caudery suffered an unfortunate injury in pole vault qualification.
But, after becoming the 35th nation to win a medal in Tokyo, the team will be optimistic of producing a strong finish to these championships.
On Wednesday night, Dina Asher-Smith, Daryll Neita and Amy Hunt reached the semi-finals of the women's 200m competition, which is missing Olympic gold and silver medallists Gabby Thomas and Julien Alfred.
Zharnel Hughes advanced in the men's event, as did defending champion Noah Lyles and Australia's exciting 17-year-old talent Gout Gout.
On Thursday, Olympic champion Keely Hodgkinson begins her bid for a first world 800m title and is joined in that event by training partner and Olympic 1500m bronze medallist Georgia Hunter Bell.