The Scanian has collaborated with several of Sweden's greatest sports profiles for decades, particularly in athletics.
When he does a quick interview about a quarter of an hour after Sjöström's powerful performance in the 50 freestyle, it's almost as if he's dancing in front of the camera.
What an enormous athlete, he says.
Largest of All Time
And states firmly:
It's not just because I've worked with her, but I consider Sarah Sjöström to be Sweden's greatest female athlete of all time, including all sports. You have to consider that swimming is a global sport. It's tough, it's devilish competition.
Wessfeldt's collaboration with Sjöström began years before the Olympic Games in Rio de Janeiro. Nearly ten years later, she is still the swimmer everyone else is trying to beat.
What drives her, do you think?
I think she still thinks it's fun to be an elite athlete. She thinks it's fun to go to training camps, to socialize in that world. She feels good about it instead of stepping into a civilian life in an office.
"Loves the Challenge"
Which of her qualities impresses you the most?
It's undoubtedly her mental toughness. When they blow the whistle to get up and stand on the starting block, many get rubber arms or legs. Then it's "Just give it to me, I'm ready" for her.
She loves the challenge, but many others get scared and some don't feel well about it. She feels good about it – and that's a damn quality. It's clear that she's also a super talent. She's smart and knows how to train, and this thing about going down to shorter distances to maintain motivation is also completely right.
There are only two who have that mental toughness. It's her and "Mondo" Duplantis. They're equally crazy.
Know Each Other Well
And you'll soon see him take a gold...?
Yes, it's completely fantastic, and they know each other well too. I know they've sat and talked, and he sat and watched her now. They trigger each other. They don't get stressed by other things around them. They can handle it.
Duplantis will receive over half a million kronor in prize money from World Athletics for an Olympic gold medal. The International Swimming Federation does not pay out any prize money, but Sjöström still earns well from her Olympic success.
Bonuses will roll in from her main sponsors. There will probably also be some new collaborations coming out of this, says Daniel Wessfeldt.