Katie Ledecky strikes a familiar pose — she has three gold medals after her victory with the women’s 4x200-meter freestyle team on Wednesday night. (Jonathan Newton/The Washington Post)

In one way, Katie Ledecky is morphing, right here in front of an international audience, into an everyone-knows-who-she-is star, the premier female freestyle swimmer not just of these Olympics but of all time. In another way, she’s just doing her part. She is an American swimmer at the Rio Games. So she must win medals.

Ledecky did that Wednesday, taking the third gold medal and fourth medal overall of her Olympics, this one as the anchor leg of the victorious women’s 4x200-meter freestyle relay team. She is delivering in the way others can only fantasize about, the latest a sizzling leg that turned what looked like a massive deficit into a walk-in-the-park advantage, taking over for teammate Maya DiRado and simply putting away Australia.

“I was prepared for being ahead, being behind,” Ledecky said. “I knew Maya put me in the right spot to get out there. I knew I had to just kind of pace myself and not jump on it too fast too early. I knew I could get it done.”

As did everyone at Olympic Aquatics Stadium. “I had no doubt in my mind as soon as I touched,” DiRado said. Ledecky’s swim Wednesday would be the performance of a lifetime for almost anyone else here, but she made it feel normal.

Michael Phelps, already the most-decorated Olympian of all-time, just keeps adding to his personal medal total at the Rio Games. (Video: Jayne W. Orenstein/The Washington Post/Photo: Jonathan Newton/The Washington Post)

When DiRado finished the third leg, the United States trailed Australia by 0.89 seconds. For some teams, this would be a crisis. Yet Ledecky’s first 100 meters were the fastest of any on the American team, and by the end, the crisis had become casual. Ledecky’s split of 1:53.74 was the fastest of any swimmer in the race by nearly a second, and she touched 1.84 seconds ahead of Australia.

“That was so much fun,” Ledecky said.

But as this 19-year-old from Bethesda pulls all this off — as she makes it just seem natural even as she defines “outlier” — she merely fits into a larger puzzle here for the U.S. swim team. That group has all but strutted across the pool deck and asked for the names of opponents who think they can keep them from the podium. There are few. Through Wednesday night, there were 20 events in which medals were available. Americans had swiped at least one piece of hardware in 18 of them.

So a moment to pause, not just for Ledecky and Michael Phelps — who Wednesday earned the top qualifying spot for the 200-meter individual medley final, to be held Thursday night — but for Ledecky’s teammates in the relay final, Allison Schmitt, DiRado (who adds a gold to silver and bronze won already) and Leah Smith. Recognize, too, Josh Prenot, who snared a silver in the men’s 200 breaststroke, just 0.07 seconds behind surprise winner Dmitriy Balandin of Kazakhstan.

A nod, too, to veteran Nathan Adrian, who couldn’t quite back up the gold he won in the 100 freestyle in London — on Wednesday, the prize went to Australia’s Kyle Chalmers in 47.58 seconds — but took bronze, just 0.27 off the pace.

Was he happy with that time, slower than he swam at U.S. trials?

Katie Ledecky developed the "gallop" in her stroke with former coach Yuri Suguiyama. It gives her an advantage in the pool over her female competitors since most do not have the strength to sustain it. (Jayne Orenstein/The Washington Post)

“No,” Adrian said. “But I’m happy with the medal.”

That is the American goal in each Olympic pool. The last time the United States didn’t lead the medal count in swimming was 1988, when it was beaten by the drug-laden East Germans. Four years ago in London, the United States crushed all comers, winning 31 medals, including 16 golds, trouncing second-best China’s 10 medals.

After five nights here, the United States is on pace to edge that total — though challenges await. The London program followed the exact order as Rio, and after five nights, American swimmers had 18 medals, eight of them gold. The relay gold was the Americans’ eighth gold here, their 21st medal overall. No other country has more than Australia’s seven medals, three of them gold.

“It’s been incredible to see what these guys are doing and just be a part of this group,” said Prenot, whose swim of 2:07.53 was something of a rarity for an American here — one that fell short of his trials time, albeit by a third of a second, “just rolling through this meet and destroying it.”

The shape of the meet was outlined in an early team meeting, in which the men’s captains — Phelps, Adrian and Anthony Ervin — spoke about how, at the Olympics, momentum matters.

“If we just get the ball rolling early on, there’s no stopping it,” backstroker Jacob Pebley said. “. . . It’s just gotten bigger and bigger as the ball’s going down the hill. It’s kind of hard not to follow that momentum when you jump on.”

Not that this has been flawless. As Ledecky, Schmitt, Smith and DiRado powered to their gold, Missy Franklin sat to the side and watched. Franklin — the breakout star of the 2012 Games, in which she won five medals — was relegated to the afternoon heat of the relay. This, after Franklin failed to even qualify for the final of the 200 freestyle earlier in the week — a development that left her delving into dark chocolate and calling her mother.

“You’re never too old to call your mom crying and asking her for advice,” Franklin said. “. . . There’s no better therapist than your mom, so getting that and just kind of resetting and knowing that I still have three more days to go and I still have a lot left to give and I’m going to give it my all.”

Ledecky has already been doing that and more. And she hasn’t been alone.

“This meet, we’re just getting started,” Ryan Lochte said. “The USA, we always show up when the time is right. . . . We’re just going to keep that going, that momentum going for the rest of the meet.”

Dave Sheinin contributed to this report.