Amazing what a little momentum will do. Inspired by the men’s hair’s-breadth win in the same event the night before, the U.S. women’s 4×200-meter freestyle relay shattered the longest-standing world record on the books by more than two seconds yesterday with a gold medal-winning swim of 7:53.42.

“That was an amazing race and we just wanted to get out there and match it,” said U.S. women’s relay member Carly Piper of the men’s swim, “and I think we did.”

And then some.

Natalie Coughlin, who had already tasted gold in the 100 backstroke, led off the relay with an amazing block-start split of 1:57.74, a time that would have placed her first in the 200-meter individual freestyle final had she swum it the night before. Coughlin opened up a full body-length lead on the field, and the race was never again close.

Piper and Dana Vollmer extended America’s lead in the middle legs, leaving anchor-woman Kaitlin Sandeno to race against history in the last 200 meters. China won silver a full 2.55 seconds back, and Germany won bronze 3.93 seconds off the American time. Australia, who beat the U.S. in the women’s 4×100 freestyle relay on the first day of competition, finished fourth, .05 seconds out of the medals.

The previous world record mark of 7:55.47 was set by East Germany in 1987, an era before extensive drug testing. Many suspected the record was drug-enabled and, until last night, thought it unbreakable.

Unlike track and field, which has seen its ranks thinned and its glamour sullied by drug-related disqualifications, swimming has been untainted by doping scandal. It hasn’t escaped controversy altogether, however.

After Monday’s men’s 100 breaststroke final, American swimmers accused Japan’s Kosuke Kitajima of performing an illegal dolphin kick at the start of his gold-medal swim. American favorite Brendan Hansen, who finished second to Kitajima by a mere .17 seconds, refused to comment on the supposed infraction. Underwater replays of the swim do show a slight dolphin kick, but it went unnoticed by referees on deck.

The flap over the first race fueled anticipation for last night’s rematch in the 200-meter breaststroke final. Quieting critics, Kitajima won gold again with an Olympic-record swim of 2:09.44 – and no dolphin kick.

Hansen managed only bronze, recording a disappointing 2:10.87 in an event in which he set a new world record just five weeks ago. Daniel Gyurta of Hungary was an unexpected interloper, sneaking in to steal silver in the last five meters with a time of 2:10.80.

In the 100 freestyle, defending Olympic champion Pieter van den Hoogenband of the Netherlands won gold with a time of 48.17, followed closely by South Africa’s Roland Mark Schoeman. Australian Ian Thorpe continued his strong showing in Athens with the Phelpsian feat of winning bronze in an event that is not among his best. Thorpe now has four medals, including two gold.

Today promises to be another winning one for Americans. Michael Phelps and Ryan Lochte went one-two in the semifinals of the 200 I.M., with Phelps setting a new Olympic record of 1:58.52. He will compete tonight for his fourth gold and sixth overall medal in six events.

Aaron Peirsol cruised to a new Olympic record and first-place finish in the 200 backstroke semifinal. He will look to add the 200 to his 100 backstroke gold tonight.

Amanda Beard topped the field in the semifinal of the women’s 200-meter breaststroke, claiming the top seed in tonight’s final. Couglin comes into the final in the 100 freestyle seated third behind new world record holder Jodie Henry of Australia and defending Olympic champion Inge De Bruijn of the Netherlands.