Three years after taking silver behind Ledecky in the 800m at Tokyo, Ariarne Titmus was again runner-up behind the American in Paris, pushing her all the way to the finish at La Defense Arena without ever leading her.
Titmus has already enjoyed a stellar Games, retaining her 400m title and taking silver in the defence of her 200m crown. But toppling Ledecky in her signature event was a bridge too far.
Though fierce rivals in the pool, the pair have affection for each other out of it, recognising the fighters within.
"You know, she's made me a better athlete. I totally respect what she has done in this sport more than anyone else," said Titmus.
"She's been winning this race since I was 11 years old and I turn 24 next month and that is just remarkable.
"I feel very honoured and privileged to be her rival and I hope I've made her a better athlete."
Titmus leaves Paris with her Olympic haul boosted to four golds, three silvers and a bronze.
She felt huge pressure to win the 400m and cried after losing her 200m title to Mollie O'Callaghan.
But the Australian said they were tears of happiness for her teammate.
"I knew what to expect physically and emotionally coming into this from learning from the last Olympics," she said of Tokyo.
"But emotionally this week I think I had so much expectation on me for the past few years to go back-to-back and continue my winning streak internationally in the 400 especially.
"I am so good at putting that pressure in a little pile and using it to my advantage to race, but then when it's off your back somehow it creeps out and just explodes.
"I'm feeling the most unbelievable sense of relief now that I'm done."
