The day's highlight was a world record for Penny Heyns in the 200 breast semis. It was the eighth world record in five days.
Australians won three of four finals contested this day, moving them in the gold medal lead with 21 (11-7-3), with the USA tied for total medals 21 (6-8-7)
It was a come-from-behind swim for Simon Cowley (AUS). In fourth place at the mid-point, he slowly moved into contention and at the 150 was half a body-length behind Tom Wilkens (USA), the leader for the first three lengths.
Cowley, with his classical long, flat breaststroke technique, moved ahead to finish a body length in front of Wilkens. Terence Parkin (RSA) held on to take the bronze.
Cowley, coached by Doug Frost, looks better every time he jumps into the pool. "Yeah, I'm pretty happy," he said. "I would like to have gone a bit quicker. But you know I will have another opportunity."
The gold was never in question. Anticipation was high after Susan O'Neill (AUS) posted the second-best-ever time in the semis, a mere half a second off the oldest record.
O'Neill won in a most convincing way with a four-second margin over Jessica Deglau (CAN) with 2:10.27 and Misty Hyman (USA) with 2:10.40.
A comparison of O'Neill's splits and the record:
The splits tell the story. Maybe O'Neill would have had more in the tank for the last lap if she had been a little more conservative in the first 100.
Coach Scott Volkers said, "She obviously wanted it badly tonight. I could see in the first 25 that it was probably not going to be simple because the stroke rate was 2 strokes per minute too high. You've got to do it easy—I guess that's the pressure and that's what she has got to learn."
Michael Klim (AUS) stayed underwater with his dolphin movement for 12 metres at the start and led the field to the turn in 23.08, under record pace. Klim held on to win in 48.90 over Neil Walker (USA) with 49.17 and Chris Fydler (AUS) with 49.42.
The American women won their only gold of the evening in this relay with the second-fastest time ever and an American record. Their time was 7:57.61, a two-second improvement over the US Olympic gold performance from 1996.
Australia was second with 8:00.67 for a Commonwealth and Australian record, and Canada was third with 8:06.86.
Semi-final winners this day were Jenny Thompson (USA) in the 100 free with 55.48 and Lenny Krayzelburg (USA) with 1:57.41 in the 200 back, with Raymond Hass (AUS) setting a national record of 1:59.08. Men's 200 IM top qualifier was Curtis Myden (CAN) in 2:02.38, with Grant McGregor (AUS), Tom Wilkens (USA), and Matthew Dunn (AUS) also under 2:03.
Penny Heyns (RSA) set her second world record of the competition in the 200 breaststroke semi-final, with 2:24.42, bettering her five-week-old time of 2:24.51. However, she was feeling the strain and said after her latest record, "I really felt like it was time to go home. I'm tired of racing.
"The focus tonight was to be really relaxed and to have fun, to enjoy every bit of the race for what it was."