USA's Allyson Felix and Carmelita Jeter headline a world-record 4x100-meter relay

Carmelita Jeter, Bianca Knight, Allyson Felix, and Tianna Madison celebrate after winning the Women's 4 x 100m

 The U.S. women got a measure of revenge against the Jamaicans on Friday night – and in stunning world-record style. The U.S. 4x100 women’s relay team obliterated the Jamaicans en route to a world record in the event, capturing gold at 40.82 – shaving .55 off the previous record of 41.37 set by East Germany in 1985. Carmelita Jeter ran a brilliant anchor leg for the U.S., opening the gap over the Jamaicans in the final 100 meters. As Jeter crossed the finish, she pointed at the track scoreboard and erupted in elation at the new world record. The foursome of Tianna Madison, Allyson Felix, Bianca Knight, and Jeter also became the first 4x100 U.S. women's relay to break the 41-second barrier.

The Jamaicans took silver at 41.41, while the Ukrainians captured bronze at 42.04.
"I knew we could challenge the world record," said Madison. "To smash it, I had no idea."
"Our names are going down in history," Felix said.
Heading into the final, the U.S. women appeared loose and ready to run, smiling and trading jokes as they headed out to take their spots on the track. It was a sign of things to come, and a big departure from the past, which has seen the U.S. women continually underachieve in the event in the Olympics. It's the first gold medal in the 4x100 for the women since 1996, and it effectively erases the awful memory of the 2008 Beijing Games, when team was disqualified for dropping a baton in the semifinals.
"It's a relief," Felix said of finally getting back to the top of the medal stand. "When we went into this, we were the most comfortable I have seen this team. We were laughing and smiling, and I have never seen the team like that."

Running out of Lane 7, Madison burst from the blocks and immediately put pressure on the Jamaicans, overtaking them by the first handoff. Felix opened a wide gap in the second leg before Knight lost some ground in the third. The Jamaicans were trailing by about 5 meters going into the final 100, but Jeter slammed the door shut down the stretch, extending the lead to 10 meters and sailing to the new world record.
"I knew these girls were going to run their hearts out," Jeter said. "I knew we were running fast. I was already pointing at the clock, saying, 'There it is.' There was a cloud hanging over us, with people saying, 'They can't do this. They're going to drop the stick.' But we did it."
The win comes after the Americans and Jamaicans traded blows in the 100- and 200-meter finals. Jeter finished second behind Jamaica's Shelly-Ann Fraser-Pryce in the 100 meters. Jamaica also took bronze in that race, with Veronica Campbell-Brown grabbing third place. The U.S. women struck back in the 200 meters, with Allyson Felix taking gold over Jamaica's Fraser-Pryce (silver), and Jeter taking bronze. In what has been a wildly successful Olympics for U.S. women's track, the team also dominated the 400 meters, with Sanya Richards-Ross winning gold and DeeDee Trotter grabbing bronze.