World records fell this day in the women's 100 fly, women's 100 breast (prelims), and the men's 200 freestyle (semi-finals).
Australia led the medal totals with 8 (4 gold and 4 silver), while the USA had 8 medals (3 gold, 2 silver, and 3 bronze).
Jenny Thompson (USA) looked very strong and fluid in her stroke, turning at the 50 in record pace with a 26.94, well ahead of Susan O'Neill (AUS) with 27.71. Coming off the turn, Thompson accelerated and slammed into the wall in 57.88, erasing Mary T. Meagher's long-standing record of 57.93 from 1981.
Susan O'Neill was second in 59.07, with Ayari Aoyama (JPN) third in 59.58.
The new world-record holder said "It's just a dream come true. I can't believe it, I'm just so psyched. I was thinking it's really amazing there's been this many new world records.
"Tonight I didn't know where I was in the race, but I just kept going and hoped that record was there. It's a fantastic pool-a fantastic meet. It's great!"
Michael Norment (USA) led the field down the first length, going to the wall in 29.06, with Simon Cowley (AUS) following in 29.20 and Brett Petersen (RSA) in 29.30.
The 18-year-old Cowley pulled ahead in the last 15 metres to take the gold in 1:02.06, with Regan Harrison (AUS) surprising in second in 1:02.26, ahead of Morgan Knabe (CAN) in 1:02.37.
"I was just happy to get on the board first. I'm a little disappointed with the time because I swam so well yesterday-but-a win's a win.
"My starts haven't been strong in the past and I have done a lot of work on them. I hit them pretty well in the prelims and the semis-but not in the final."
Lindsay Benko (USA) was in the lead for the first 100 with 59.80, ahead of Brooke Bennett (USA) with 1:00.20. Bennett then moved into the lead, which she maintained for the rest of the race, winning in 4:08.39 to Benko's 4:08.75. Bennett's time was her personal best by over two seconds. Claudia Poll (CRC) was third in 4:11.53.
When asked what this win meant to her 12 months before the Olympics, Bennett replied: "I think it means a lot-especially to get a good feel in the water-know what it's going to look like next year."
Curtis Myden (CAN) was the favourite with the fastest time of the year. Matthew Dunn was not given much of a chance of winning after breaking a leg in May and missing his usual aerobic preparation.
Dunn won in 4:16.54 to Myden's 4:16.77. Tom Wilkens (USA), who led for the first half, had be content with the bronze medal in 4:18.58.
Dunn appeared stunned at the result and the great race it turned out to be. When asked where it hit him, he replied "In the legs. Last time I walked like this I had a broken leg. I'm just rapt. I had a really disjointed preparation and I'm happy to come away with the win."
Dunn on Myden: "Yeah, he's a good competitor. It wouldn't have been the race it was without Curtis."
Semi-finals were held in the 100 backstroke, with two Japanese women posting the fastest times-Mai Nakamura with 1:02.07 and Noriko Inada with 1:02.27.
A very fast men's 200 freestyle semi-final had Michael Klim (AUS) on record pace in the first heat, posting a personal best of 1:46.82, followed by a record swim by Ian Thorpe in the next heat. His 1:46.34 bettered Grant Hackett's 1:46.67 from last March. Thorpe's splits were 25.03, 52.50, and 1:19.36.
"It's going to be a great race tomorrow night," Thorpe predicted.