Los Angeles - Five-time Olympic swimming champion Katie Ledecky followed up her world record-shattering 1 500m freestyle performance with the second-fastest 400m free in history at the Pro Swim Series in Indianapolis on Thursday.
Ledecky won the 400m freestyle in 3:57.94, second only to her own world record of 3:56.46 set in winning gold at the 2016 Rio Olympics.
She returned to the pool later to finish fifth in the 100m freestyle.
"I had two really great swims," said Ledecky, who sliced five seconds off her own 1 500m free world record on Wednesday with a time of 15:20.48.
"I was just trying to make a few improvements off of this morning's swims, just pacing and being a little more controlled.
"I still had a little too high of a tempo in the first 50m of my 400m, but overall I was really pleased with the swim, the time."
This week's meeting in Indianapolis is the 21-year-old star's first since turning professional following the NCAA collegiate championships in March.
Other US Olympians touching first on Thursday included Nathan Adrian in the men's 100m free in 48.69, Kelsi Dahlia in the women's 100m butterfly in 57.38, Gunnar Bentz in the men's 100m fly in 53.03 and Melanie Margalis in the women's 200m breaststroke in 2:24.62.
Canadian Olympian Taylor Ruck won the women's 100m freestyle in 53.42.
Ledecky, who won gold in the 800m at the 2012 Olympics and followed it up with four golds and a silver at the Rio Olympics two years ago, has a busy schedule over the remaining two days of the meeting.
She's entered in the 200m and 800m freestyle and the 200m and 400m individual medley.