Katie Ledecky Upset by Ariarne Titmus at 2019 World Swimming Championships

Australia's Ariarne Titmus beat Katie Ledecky in the 400-metre freestyle at the 2019 World Swimming Championships in Gwangju, South Korea, on Sunday.

Ledecky was chasing a fourth straight title and led going into the final lap, but Titmus produced a strong finish to surge past the American and win in a time of three minutes and 58.76 seconds.

American Leah Smith came in third to take the bronze and the final place on the podium.

FINA shared highlights of the race, including the dramatic finish:

The result is a shock, as Ledecky has dominated the event throughout her career:

The American produced the slowest last lap of any of the eight swimmers in the race and spoke afterwards about why she had struggled heading towards the finish, per News.com.au:

"I just got to the last turn and felt like I just tightened up. My legs were just dead, and obviously, Ariarne took advantage of that and had a heck of a swim. Obviously, this stings a little; it's unfamiliar and different."

Titmus led for the first 200 metres but was then overtaken by Ledecky. However, the Australian produced a brilliant final lap to defeat her rival by one minute and 21 seconds.

The 18-year-old offered her thoughts on a stunning win after the race, per News.com.au:

"I knew that I properly had that in me. I feel pretty normal; it was just a swimming race. There was no pressure really coming into this race. I just wanted to fight as hard as I could—in that last 50 metres, I gave it everything."

Titmus' shock win over Ledecky drew plenty of praise:

Ledecky will return to action next in the 200 metres, where she will once again come up against Titmus.