Tokyo — Caeleb Dressel got started on his quest for six gold medals in swimming, while Katie: second place.
Dressel led off a U.S. victory in the men's 4x100-meter freestyle relay Monday at, easing a bit of America's sting from Ledecky's first Olympic loss.
Australian Ariarne Titmus - nicknamed the "Terminator" - lived up to her billing when she chased down Ledecky in the 400 freestyle to win one of the most anticipated races of the Summer Games.
Titmus, who trailed by nearly a full body-length at the halfway mark of the eight-lap race, turned on the speed to touch in 3 minutes, 56.69 seconds. It was the second-fastest time in history, surpassed only by Ledecky's world record of 3:56.46 from the 2016 Rio Games.
The defending Olympic champion settled for the silver this time in 3:57.36 -- the fourth-fastest time ever recorded and her best performance in three years. Just not good enough.
Then the spotlight shifted to Dressel, who's been hailed as the successor to Michael Phelps.
Dressel put the U.S. out front, and the three who followed him in the relay made sure it stood up.
"I felt good the whole way, I knew I had to get my hand in the wall first and get some clean water," Dressel said. "And everyone did their job. It's a relay for a reason, it's four guys for a reason, it's certainly not just me. It's certainly not just one guy."
The 24-year-old, tattooed Floridian swam the first leg in a blistering 47.26. Blake Pieroni and Bowe Becker kept the Americans out front before Zach Apple turned in an anchor leg of 46.69 to leave no doubt at the end.
The U.S. won in 3:08.97, the third-fastest time in history. Italy took the silver in 3:10.11, with the bronze going to Australia in 3:10.22.
"The scariest part was my leg for myself, because I had control over that," Dressel said. "I knew they were going to get the job done, I wasn't scared at all. Especially when Zach hit the water. I saw him break out and I knew it was over."
Apple climbed from the pool to an embrace from Dressel, who is set for a grueling schedule of three individual events and three relays in Tokyo.
One down, five to go.
Ledecky's disappointment was a downer for the Americans, who won six of 12 medals on Sunday but were shut out in the first two finals Monday.
Torri Huske and Michael Andrew just missed medals with fourth-place finishes, then it was Ledecky settling for the second spot on the podium - a stunner for perhaps the greatest women's freestyle swimmer in history.