Norway's double world champion hits last hurdle on way to second fastest time in history, then comes back to win flat 400m
Had the Norwegian star not hit the last hurdle, he probably would have broken Young's time set in the Barcelona 1992 Olympic final.
As it was, he had to settle for the second quickest time in history, 46.87s, just nine-hundredths adrift of the oldest men's track record in athletics.
Just ninety minutes later, he was back on the track winning the flat 400m.
"It felt really good, especially the hurdles. I'm really really proud of doing what I did." - Karsten Warholm
Elsewhere, Britain's women had a middle-distance double courtesy of Laura Muir and fellow Scot Jemma Reekie.
World 1500m champion Timothy Cheruiyot again got the better of Warholm's fellow Norwegian Jakob Ingebrigtsen.
Crowd favourite Mondo Duplantis won the pole vault with 6.01m but failed with three attempts at 6.15m.
And Thobias Montler was denied a home victory by the new long jump 'Final 3' format - which saw the top three competitors after five rounds have a jump-off - with South Africa's Ruswahl Samaai coming out on top.
Karsten Warholm has been gunning for Kevin Young's 400m hurdles world record for some time now.
And surely it is only a matter of time before he breaks it after this near-miss in Stockholm.
Warholm broke the 300m hurdles world best in a solo run in Oslo in June, and he was effectively on his own again here as he ran in lane eight.
He was blisteringly quick away and soon had his rivals toiling in his wake.
But he clipped the last hurdle which almost certainly cost him that world record on this occasion.
The 24-year-old did not give any interviews after that disappointment, but he came back 90 minutes later to run - and win - the flat 400m.
Again in lane eight, Warholm took a confident look across on the final bend before powering away for this second win of the afternoon in a season's best 45.05s.
Laura Muir was an impressive winner of the women's 1500m with 5000m world champion Hellen Obiri well down the field.
The Scotswoman kicked away with a lap to go and clocked 3:57.87, the fastest time in the world this year, well clear of Laura Weightman second and Melissa Courtney-Bryant for a British 1-2-3 not seen since the heady days of Coe, Cram and Ovett.
Despite the windy conditions, Muir was delighted with her performance telling reporters, "I felt strong in the last lap and was able to work well into the wind and ultimately come away with a clear win.
"My strength is my endurance and I really wanted to run fast today."
Her training partner Jemma Reekie then took the 800m, coming clear of world silver medallist Raevyn Rogers for victory in 1:59.68.
Femke Bol continued her excellent form in the women's 400m hurdles, the Dutchwoman clocking 54.68s to beat Anna Ryzhykova just as she did last week in Hungary.
Mondo Duplantis was in a class of his own in the pole vault, making light of the gusty winds.
World champion Sam Kendricks could only manage 5.53m, failing three times at 5.73m, to take third with Ben Broeders of Belgium second on 5.73m.
Sweden's world record holder cleared 5.73m and 5.83m on his first attempt to win the competition before delighting the home fans with a stadium record of 6.01m, again at the first time of asking.
Kendricks said afterwards, "It was a little windy out there but it didn't hurt Mondo at all! I love competing against Mondo, we've both been through our ups and downs in the past and he's on a real high right now and I'm just trying to catch back up to him."
World 800m champion Donavan Brazier was too good again over two laps, beating Marco Arop of Canada in a fast time of 1:43.76.
In the men's 1500m, Timothy Cheruiyot was again pushed hard by Jakob Ingebrigtsen.
But as he did last week in Monaco, Kenya's reigning world champion just seemed to be able to go through the gears to repell the Norwegian teenager as he took victory in 3:30.25.
Australia's Stewart McSweyn stayed with the big two most of the way and was rewarded with a personal best of 3:31.48 in third.
Heptathlon world champion Katarina Johnson-Thompson competed in both the 100m hurdles and the long jump in Stockholm.
The Briton was sixth in the 100m hurdles in 13.94s with Italy's Luminosa Bogliolo taking victory in 12.88s.
She was more competitive in the long jump with 6.52m her best distance for another sixth-place finish.
The new long jump format saw the top three jumpers from the first five rounds go into a decisive sixth and final round.
Johnson-Thompson said, "The long jump was much better than the hurdles - in the hurdles I hit one, really really hit one, with my knee, and almost fell over so I was happy to stay on my feet.
"This was my first long jump competition of the season. Yeah it was good."
The men's long jump saw Thobias Montler finish second despite jumping furthest.
The Swede twice recorded 8.13m to go into a jump-off with South Africa's Ruswahl Samaai and Kristian Pulli of Finland.
And it was Samaai who took victory with 8.09m as Montler only managed 8.06m and Pulli committed a foul.
After being denied a home win, Montler said, "I'm happy with my four times over 8m, but I'm not so happy with the competition system!"
And Samaai later made public his displeasure with the new format.
Ajla Del Ponte backed up victory in Monaco with her seventh consecutive win over 100m.
The Swiss sprinter triumphed in 11.20s to win from the Netherlands' Marije van Hunenstijn with Cote d'Ivoire's twice world 100m medallist Marie-Josee Ta Lou third.
And there was a Ukrainian 1-2 in the women's high jump with Yaroslava Mahuchikh, who turns 19 next month, clearing 2.00m with her third attempt to win from Yuliya Levchenko.