The 24-year-old dragged his trailing leg on the final hurdle in Stockholm in August to finish in a world-leading 46.87 seconds -- 0.09 seconds shy of Kevin Young's world record, a mark he has inched ever closer to throughout his career.
"Being really happy and really disappointed at the same time -- it's a weird feeling," Warholm tells CNN Sport as he reflects on his season.
"I was really, really happy of course with the race in itself. But stumbling into the last hurdle and just looking at the time, knowing that most likely I spoiled my chances of a world record right there ... I think I've never felt that way before."
Young's world record, set at the Barcelona Olympics, has stood for 28 years, the longest-standing record in men's track running.
The American recently said he feels it's "about time" his record is broken, and a glance at the all-time list suggests he might not have to wait much longer.
Warholm has run four of the 10 fastest times in the event's history, while his two closest rivals, Rai Benjamin and Abderrahmane Samba, make up the only other athletes to ever run under 47 seconds.
Between those three, the race for the world record is very much on.
"This is going to be really, really tough competition-wise," says Warholm, who took the world title ahead of Benjamin and Samba last year.
"I think in 400m hurdles we are in for a real treat because everybody wants this right now. I think it's going to be like the moon race between the United States and Russia -- it's going to be crazy."
It will take more giant leaps than small steps to triumph in hurdles' version of the Space Race, but as with any contest -- athletic or cosmic -- it is rivalry that helps fuel progress.
"It's really important to have competition, somebody pushing you and somebody keeping you on your toes, I really like that," Warholm adds.
"I'm thankful for my competitors -- even though I want to beat them, of course."
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Quality training and being best friends with the coach
Warholm, who originally competed in decathlon, achieved a major breakthrough when he won gold at the 2017 World Championships in just his second full season as a 400m hurdler.
The then-21-year-old's reaction to that victory was iconic, clawing his fingers down the side of his face with his mouth agape in disbelief. He had run hard and fast straight from the gun, a trademark of his performances over the years.
An expressive persona has become a common feature of Warholm's races, too. The Norwegian will thump his chest and roar words of self-encouragement as he's introduced to the crowd on the start line -- psychological preparation for what lies ahead.
"When I look at my races, I get sort of embarrassed because it looks silly, but at the same time it works for me and it's a part of my routine," says Warholm.
"When I'm in training I only race against myself and the clock. I'm just trying to get that adrenaline and trying to get the high quality. I started it in training, getting
