Katie Ledecky, 19, finished third in her semifinal heat of the 4x100 freestyle Thursday night in Omaha but fell to seventh by the time the second heat finished. (Tom Pennington/Getty Images)

The U.S. women’s 4x100-meter freestyle relay team could use a sudden infusion of talent, some prodigious world beater to fall in its lap in time to take on the vaunted Australians at the 2016 Rio de Janeiro Olympics. And sure enough Thursday night, there was Katie Ledecky, the freestyle phenom but a relative newcomer to the sprint game, in Lane 3 of the first of two semifinals of the 100 freestyle at the U.S. Olympic swimming trials — the race that helps determine the relay personnel.

But when the whitecaps churned up by the swimmers had faded at CenturyLink Center, Ledecky, 19, had touched the wall third in her heat, and she fell to seventh by the time the second heat finished. Abbey Weitzeil paced the qualifying with a time of 53.57 seconds, followed by Simone Manuel at 53.64. Ledecky’s time of 54.04 matched her time in qualifying heats Thursday morning.

Though there was speculation Ledecky would scratch from the final Friday night, and she was noncommittal about it immediately after her semifinal — she faces a preliminary heat Friday morning in the 800 free, her best event — a USA Swimming official confirmed late Thursday night she would swim the final. A top-six finish likely would secure her a spot on the 4x100 free relay.

“I feel like I can go faster,” she said after the semifinal.

The 100 free is an anomaly in what has become, over the past year or so, Ledecky’s core meet program — the rare event in which she is not the dominant factor. Her best time this year, a 53.75 in Austin in January, was good enough to earn the fourth seed in Thursday morning’s preliminaries, but she has no designs — or perhaps few designs — on finishing in the top two in the final to earn a spot in the event in Rio. The 100 exists for Ledecky almost solely for the purpose of making a relay team.

Ledecky’s goals underwent a forced recalibration after the London 2012 Olympics. At age 15, she already was not only an Olympian but an Olympic gold medalist in the 800 free. Her goals could barely keep pace with her accomplishments. Coming out of London, she began setting new goals for 2013, and near the top of the list was to become a stalwart of at least one U.S. relay team.

She did just exactly that in the 4x200 freestyle relay, earning her spot in time for the 2013 world championships, where the United States won the gold, and ascending to the anchor leg by 2015 worlds, another gold medal. Here at the Olympic trials, she underscored her dominance in the 200 free Wednesday night by not only sealing her position in the individual event for Rio but retaining her status as the anchor leg of the relay.

“That was a goal of mine,” she said. “One of my first goals after London was to make the relay in [2013] at worlds, and obviously each year you always want to requalify for that relay. Watching all the races in London, I was inspired by all my teammates and wanted to get in there and race. And it’s pretty cool now that I will be a lot busier in Rio and won’t get the opportunity to cheer that much in the stands.”

Perhaps it was asking too much of Ledecky, the world record holder in both the 400 and 800 freestyles, to expand her repertoire all the way down to the 100 so soon after making it an important part of her training. In this era of specialization — when distance swimmers and sprinters are considered separate species — only an immense talent as Ledecky even would have contemplated it.

The women’s 4x100 free relay — and the entire U.S. sprint squad — certainly could use Ledecky’s help. The last few Olympic cycles have been a glaring disappointment for American female sprinters, with no medals of any kind in Olympics or world championships in the 50- or 100-meter freestyles since 2008, when Dara Torres took silver in the 50 and Natalie Coughlin won bronze in the 100. (The 4x100 relay, though, took silver in Beijing in 2008 and bronze in London in 2012.) The last American gold in one of the individual sprints was Amy Van Dyken’s win in the 50 in Atlanta in 1996.

The landscape this summer, too, appears bleak for the Americans. None are ranked among the top nine in the world this year in the 100 — Weitzeil’s 53.57 on Thursday night ranks 10th. (Madison Kennedy, at seventh, is the highest-ranked American in the 50). Australians own three of the top four rankings this year in the 100 — all of them under 53 seconds — which portends a monster relay team in Rio, with many observers already assuming the rest of the world is competing for silver.

“I just need to figure some things out to be that 52 that I want,” Weitzeil said Thursday night. “USA — we need a 52, so I’m trying to be that.”

It might have been comforting for the Americans to have seen Ledecky riding in to save the day, and eventually, as she continues to creep down in distance, she may become the sprint champion they need. But that day is probably not coming this summer.