Phelps collected his second title of the championships with a thrilling win in the four-lap race while Aaron Peirsol and Kate Ziegler also struck gold for the United States.
Peirsol was untroubled in retaining his 100m backstroke crown while Ziegler slashed more than 10 seconds off her personal best to win the women’s 1500m freestyle, the longest event on the programme.
Kirsty Coventry won Zimbabwe’s first world title with a stunning upset in the women’s 100m backstroke while Australia’s Leisel Jones ended her frustrating run at major championships by winning the women’s 100m breaststroke.
But all eyes were again on Phelps and his clash with Australian long-distance star Grant Hackett, billed as one of the highlights of the meet.
The pair had been expected to clash in the 400m on the opening night of competition but Phelps’s shock failure to reach the final allowed Hackett to cruise to victory, becoming the first person to win gold medals at four world championships.
Phelps, who had been hoping to win a record eight titles in Montreal, made amends for his 400m flop by winning a relay gold on Sunday night then rebounded to win the 200m on Tuesday in a time of one minute 45.20 seconds.
“Everything here has been a big learning experience for me,” Phelps said.
“Everything that’s happened hopefully will help me on the road to Beijing.”
Hackett, who had to swim the 800m heats earlier in the day, took the silver in 1:46.14 while South African Ryk Neethling was third in 1:46.63 after leading the field through the first 100m under world record pace.
“You can’t take away from his (Phelps’s) performance,” Hackett said.
Phelps did the double yesterday morning, easily qualifying in both the 100-metre freestyle and 200 individual medley. One night after his first individual victory of the meet, Phelps was back in the water managing that fine line between conserving energy and making sure he didn’t take things too easy. No problem.
Phelps managed a time of 49.04 seconds in the 100 free, making him the third-fastest qualifier behind Italy’s Filippo Magnini (48.97) and South Africa’s Ryk Neethling (49.04).
Phelps returned about an hour later for the 200 IM, again managing the third-best time in one of his strongest events. His time of 2 minutes, 0.30 seconds was far off his world record standard but easily good enough to send him on to the semifinals.
Peirsol, 22, became the first man since East German Roland Matthes in 1973 and 1975 to win the 100m backstroke at two world championships after he added to his first title from Barcelona two years ago.
The Californian, who won three gold medals at last year’s Athens Olympics, led all the way to take the gold in 53.62, just outside his world record of 53.17 set in April.
Ziegler had only qualified seventh for the 1500m final and had to swim from the outside lane but also led all the way to claim her first world title.
The 17-year-old won in a time of 16:00.41, making her the third fastest woman in history, while Italian Flavia Rigamonti finished second and Brittany Reimer of Canada third.
Coventry flashed home on the last lap after being third at the turn to take the women’s 100m backstroke title in 1:00.24 after the hot favourite Natalie Coughlin faded badly in the last 15 metres.
Coughlin, the world record holder and reigning Olympic champion, had to settle for third as Coventry and 2003 world title winner Antje Buschschulte from Germany both stormed past her.
Coventry is the first Zimbabwean to win a world title.
Jones also flew home in the last 15 metres to win the 100m breaststroke gold just 24 hours after she lost her world record to American teenager Jessica Hardy.
Hardy, who broke Jones’s world record in Monday’s semis, was in front at the turn but could not hold off the fast-finishing Australian whose winning time of 1:00.25 was just 0.05 outside the new world record.