LONDON — What look was supposed to sweep across the face of Allyson Felix once she realized what transpired Wednesday night, when Americans won medals in rapid succession on the track? Astonishment or joy? Relief or bliss? All of it, rolled into one?

Felix has been in her sport’s consciousness for the better part of a decade, since she was a teenager, when it seemed she could run as fast as she wanted in whatever event she chose.

Careers, though, have a funny way of unwinding, and competitive meets can likewise unfurl strangely over the course of a week. So on a night with a pace that felt something like a cattle auction, Felix, for once, smiled broadly at the end of an Olympic sprint, and the U.S. track and field team grabbed a meet that was slipping away and completely turned it around with a staggering seven-medal haul that included three golds.

“Just a flood of emotions,” Felix said.

Individually, sure, but for the team as a whole as well. Felix’s victory in the women’s 200 meters — a victory that now supplants her silver medals in 2004 and 2008 — was the centerpiece of a night that also brought gold for Brittney Reese in the women’s long jump and Aries Merritt in the men’s 110-meter hurdles.

And the Americans merely beat other Americans, because Carmelita Jeter took bronze behind Felix; Janay DeLoach did the same behind Reese; and Jason Richardson followed Merritt to the line for silver.

Throw in a silver in the women’s 400-meter hurdles for Lashinda Demus — who was all of seven hundredths of a second behind gold medallist Natalya Antyukh of Russia — and the U.S. had one of the best nights in its Olympics track and field history.

With three days remaining, Americans already have 20 medals at Olympic Stadium, 11 from the women alone. That’s a bigger haul for the U.S. women’s track and field team in any Olympics other than 1984, which was diluted by the Soviet-led boycott.

“We come from such a rich legacy and history,” Felix said. “So just to do our part, and come out on top is just special. We just want to take care of business for our country.”

Truthfully, though, before the relays begin, track is an individual pursuit. In that regard, Felix had the most intriguing business to which to tend. A look at her stride, effortless and pure, would suggest her walls are lined with golds. In a sense, they are.

“I always thought the world championship golds were pretty exciting,” said her mother, Marlean. And indeed, her individual golds from worlds in 2005, 2007 and 2009 – all in the 200 — shows Olympic gold was possible, even probable.

But Felix was honest with herself about her own narrative here. “The moments that motivated me most was losing on the biggest stage,” she said, “and just never forgetting that feeling.”

Wednesday night, running inside her by two lanes, was her de facto nemesis, Veronica Campbell-Brown of Jamaica. Eight years ago in Athens, then four years ago in Beijing, Campbell-Brown took the race out hard. Felix glided behind her, unable to catch up.