Sitting next to each other at a press conference on Saturday, Ledecky has the last laugh.

The American won the 800-metres freestyle from silver medallist Titmus.

Titmus laughed longest.

The Australian won the 200m and 400m freestyles over Ledecky.

And both are laughing, as friends do, at their battles being portrayed as an intense rivalry.

"It's not about a one-up on Katie or that type of thing," Titmus said.

"To have her in the field, the great swimmer she is, it probably makes it a little bit more satisfying."

Titmus, on Olympic debut, took the 200m-400m gold double, the 800m silver and a bronze in the 4x200m freestyle relay.

Ledecky, at her third Olympics, took the 800-1500 double and the 400m silver. Aged just 24, she is a seven-time Olympic champion.

"This is my first Olympics and I know how tough it has been to get here," the 20-year-old Titmus said.

"And how tough it is to win a gold medal, especially when I feel like I had one of probably the hardest person to beat in my races.

"It has been really overwhelming for me, this week, it's tough ... the whole hype around the Olympics just adds that extra tiredness and emotional drainage.

"So to look at Katie and see what she has achieved at three Olympics, I mean, I would dream of that."

In June at Australia's selection trials, Titmus got within touching distance of Ledecky's world records.

The American, solid but not spectacular at the US trials at the same time, took notice.

"She swam so fast at her trials, and I was a little off at my trials," Ledecky said.

"And it really pushed me to work really hard for that period in between trials and here."

Titmus at the trials virtually swam alone: Australia's domestic fields can't keep up.

"Domestically you have to push yourself and swim with instinct with no-one really around you," she said.

"To actually be in a battle helps you to swim faster.

"That was the thing I was most looking forward to coming here, being able to actually have a good race and see how fast we can go."

Ledecky concurred.

"To have somebody right there who is swimming very similar times, you just have that mutual respect," she said.

"We're very friendly. There's nothing between us.

"We're just going to keep moving forward and follow our own paths and work towards our own goals.

"And if we happen to get side-by,-side, we're going to put up really great races and be fierce competitors when we dive into the water.

"But we're always going to have, I hope we always have, that great respect for each other."

Australian Associated Press