Rome:
Six world records tumbled on the first night of World Championship swimming, but with the record books turned upside down Michael Phelps ended up in a familiar spot - the winner's podium.
The half-dozen records yielded in the evening's eight events at the Foro Italico included two in one event, and while Phelps wasn't part of the spree he did have a role in America's upset victory in the men's 4x100m free.
Italy's Federica Pellegrini thrilled home fans by lowering her own world mark to win the women's 400m freestyle, and German Paul Biedermann also notched a world record in winning the men's 400m free.
The Netherland's Olympic gold medal-winning women's 4x100m freestyle relay team lowered their world record to add a world title to their list of accomplishments - overcoming an individual 100m freestyle world record for Germany's Britta Steffen in the lead-off leg of that race.
Swedish teenager Sarah Sjostrom and American Ariana Kukors nabbed their world records in semi-finals - Sjostrom in the women's 100m butterfly and Kukors in the women's 200m individual medley.
The men's 4x100m free relay didn't produce a world record, just scintillating racing in which an American team led by Phelps and anchored by Nathan Adrian triumphed, Russia snatched silver and France's vaunted freestyle sprinters were relegated to bronze.
"When we come into a meet we have a goal to win all three relays, and I think this is a perfect way to end day one," said Phelps, who will swim a relatively light programme of three individual events and three relays here.
Adrian's final leg echoed Jason Lezak's gutsy performance in Beijing, when he caught Bernard on the final lap to secure the victory and keep Phelps on course to win a record eight gold medals at one Olympic Games.
The record-shattering exploits were widely predicted at the last world meeting to allow the current generation of high-tech supersuits.
FINA, world swimming's governing body has pledged to roll back suit technology starting in 2010 after claims the suits enhance performance artificially, but Sunday's results promised a frenzied farewell to the controversial attire.
Three world records fell in the first three events, starting with Sjostrom's 56.44sec in the women's 100m fly semis. That broke one of the oldest records on the women's books, the 56.61sec set by Inge de Bruijn of the Netherlands at the Sydney Olympics in 2000.
Next up was Biedermann, whose 400m free victory in 3:40.07 broke an iconic mark, the 3:40.08 set by Australian legend Ian Thorpe in 2002.
Biedermann powered past Tunisian Oussama Mellouli to lift the crown, Mellouli finishing second and China's Olympic silver medallist Zhang Lin third.
"I just said to myself, don't let him go, stay at his feet, and at the end I was really glad to beat him," Biedermann said of Mellouli.
Biedermann seemed stunned to have replaced one time idol Thorpe in the record books.
"I watched him at home on TV and never expected to swim that fast or beat his world record but even if I did beat one of his world records, he is still a living swimming legend," he said.
Reigning world and Olympic champion Park Tae-hwan wasn't in the mix, having failed to qualify for the final.
World record number three went to unheralded Kukors, who only got into the race when one of the two US women who qualified at trials pulled out. She clocked 2:07.03, to better a mark held by Australian Stephanie Rice, who settled for the second-fastest semi-final time.
For more than 11,000 Italian fans, however, the high point was Pellegrini's 400m free triumph, with a time of 3:59.15 that made her the first woman to break the four-minute barrier.
Dogged Briton Joanne Jackson, who held the world record earlier this year, settled for silver ahead of compatriot and Olympic gold medallist Rebecca Adlington.
Addlington said she didn't regret her decision to stick to the Speedo LZR Racer suit, a 2008 marvel that spawned the current crop of supersuits but has been outdistanced.
"At the end of the day a suit's not going to swim by itself, it's the person that's in the suit that's out here doing the work," she said.
"I'm really comfortable in a LZR, I know it's not going to dig in. It's the same with Jo (Jackson), she's really comfortable in that suit and you've got to be comfortable over 800m."
In the women's relay, the Dutch quartet of Inge Dekker, Ranomi Kromowidjojo, Frederike Heemskerk and Marleen Veldhuis rallied from fifth after the first leg to win in 3:31.72.
Germany settled for silver, despite the record-breaking exploit of Steffen, who led off in an individual record of 50.22sec, and Australia captured bronze.
Germany's time of 3:31.83 and Australia's 3:33.01 were both under the previous relay world record.