Ariarne Titmus and Katie Ledecky have established an intense rivalry in the pool. (Al Bello/Getty Images)

Ariarne Titmus doesn’t know when she’ll swim against Katie Ledecky again.

The newly minted world record holder in the 400-meter freestyle – a record that had been Ledecky’s – is skipping this month’s world championships in Budapest. She remains undecided for August’s Duel in the Pool, which will pit Australian and American swimmers against one another.

The Australian has her eyes on the Commonwealth Games starting in late July and a possible break after that, and she admitted to some mental fatigue surrounding her rivalry with Ledecky.

“Still deciding on Duel in the Pool,” she told reporters Wednesday. “I know people are looking to see if I’ll be racing Katie, it’s always a very highly anticipated battle.

“But the battle with her comes with external pressure. Last year was huge for me, mentally too, a lot of pressure around my races. I didn’t really want to have to deal with that pressure again [in Budapest].”

While many are looking to Titmus and Ledecky to continue their competition in the leadup to the 2024 Paris Olympics, Titmus sees more than just the two of them as possible threats. At just 15 years old, Canadian Summer McIntosh is the third-fastest in the 400 this year with a time of 4:01.59 and could become even faster as she gets older.

“I remember when I was Summer’s age, I wasn’t swimming 4:01, 4:02,” said Titmus. “And she doesn’t have the strength yet that we have and when she does she is going to be a force to be reckoned with.

“There is this unbelievable depth. In Paris, the race won’t just be between Katie and I.”