Caeleb Dressel makes no apologies for being "a little bit of a weirdo", with the American swimming sensation determined to tackle his Olympic mountain on his own terms.

A first individual gold for Dressel arrived on Thursday when he edged out Australian rival Kyle Chalmers in a rollicking final of the 100 metres freestyle.

After the race, Dressel was left tearful when he was connected to family at home on a video link provided by a US broadcaster, with his parents and wife Meghan back in Florida celebrating the victory.

Dressel believes he has to cut down such contact to a minimum in Games time. He is a four-time gold medallist now, after two relay triumphs in Rio five years ago and another in Tokyo preceded his solo swim to glory.

For the 24-year-old, what matters most at these times is finding and maintaining race focus.

Caeleb Dressel

"I don't talk to many people at these meets. I'm kind of a loner, a little bit of a weirdo," Dressel said.

And that's why Meghan has to get by without a guaranteed daily call home from Japan.

"You have to manage your emotions. I can't be calling them every night because I cry a lot," Dressel said. "I'm an emotional person. I can't be calling them and exerting that energy. It's got to be put into my swimming."

It seems to be so far, so good on that front, with an Olympic record of 47.02 seconds bagged on Thursday and the prospect of more medals to come.

Dressel was widely expected to be a major star of Tokyo 2020 and is handling the stress of that situation, albeit if beneath the surface there is a constant battle to direct his energy.

"I'm pretty good at putting a face on," Dressel said. "Pressure's fine; it's when you turn it into stress, that's when it becomes a problem.

"My first couple of swims, I was turning the pressure into stress. I feel like the semi-final of the 100m free and that final there, I was starting to find my groove a little bit, and it's about time to be honest.

"I know my name's thrown out there and i understand it. I could care less about it, it's just something that comes with the sport when you're on top of the podium."

Dressel has gone silent on Instagram, deliberately staying away from social media, again saying that is "energy I don't need to be exerting".

And he was thrilled by how he swam against Chalmers, saying he "wouldn't have changed a thing about that race", even though it was practically a photo finish.

Chalmers, sharing a news conference podium with Dressel, said: "There's nothing I could have done more.

"It's been talked up as more than a swimming race for a while now. Caeleb and I have a fairly fierce rivalry.

"We do enjoy racing against each other and bring the best out in each other, so it's almost a relief to get it done now."