With two more world records, the total was six after three days of swimming.
World records fell to Ian Thorpe (AUS) in the 200 free and Lenny Krazelburg (USA) in the 100 back. Australia led with 13 medals (6-6-1), followed by the USA with 11 (4-3-4) and Canada with 5 (1-1-3).
An Australian record and a poor touch resulted in a rare tie for the gold.
Mai Nakamura (JPN) had the early lead, touching first at the 50 in 29.74, with Dyana Calub (AUS) second with 29.95. Calub finished strongly and seemingly won. But in a dramatic turn of events, the scoreboards failed to register the times.
After a delay of several minutes and to the surprise of the crowd, Calub and Nakamura were both shown with the same time of 1:01.51-the computer was not able to separate them. Gold medals went to both swimmers. Barbara Bedford took the bronze medal in 1:01.76.
Meet Director Roger Smith, a FINA Vice-President, said of the scoreboard problem, "There was a malfunction between the touch pad and the electronic scoreboard; so we checked the (paper) tape and the video. Both results were exactly the same."
Mai Nakamura said, "I lost with a poor touch on the wall. This is a problem I have and I must fix it."
Calub was overcome with her first international medal. "I was hoping this meet was going to my best so far and it has been. I just swam my own race in my own lane and didn't worry about anyone else. I'm very happy with the time, which broke Nicole Stevenson's Australian record."
The race started with Ian Thorpe and Michael Klim stroke for stroke on the first lap, with Klim turning in 24.83 ahead of Thorpe in 24.92. Thorpe looked very smooth and moved ahead in the second 50, splitting 52.01 at the 100. Klim was still at Thorpe's shoulder with a 52.14. Ryk Neethling (RSA) was in third place.
Klim could not keep up in the last lap. The amazing Ian Thorpe had done it again, blowing his opposition out of the water with a tremondous last lap to set a record of 1:46.00.
After his third world record in three days, Thorpe was asked if it gets any better than this. "I don't think so. I never believed I could do it this fast. Now it's done it has been all worthwhile."
Lenny Krayzelburg (USA) went ahead of Jeff Rouse's world-record pace of 26.32 with a fast 25.97, to write his name into the record book with a winning time of 53.60.
Matt Welsh (AUS) improved again to take the silver in 55.13 over teammate Josh Watson, who was third in 55.18
"That was my goal," said Krayzelburg. "To set a new world record, but I kind of surprised myself here. It's an awesome pool-definitely the best I've raced in. I'm really looking forward to coming back next year."
It was all Penny Heyns again as the South African swam with her customary power stroke. However it was not to be a new record this time, winning with a 1:07.08, slowest of the three rounds (1:06.52 prelims and 1:06.99 semis).
"I can't say I'm disappointed in my time," Heyns said. "Obviously I was hoping to go a little faster than I'd gone last night. So far I've had a really brilliant month of racing. Each race is an opportunity to learn something. I think I made a couple of little mistakes, like my finish."
Megan Quann (USA) was second in 1:08.54 69, with Kristy Kowal (USA) third in 1:08.56.
In semi-finals, Susan O'Neill posted the fastest time in the 200 free with 1:59.88 and Joanne Malar (CAN) swam a personal best and the fastest time this year with a 2:13.95 in the 200 IM. Tom Malchow (USA) had the fastest time in the 200 fly with 1:55.76.