Phelps, the American swimming superstar, picked up the 18th and 19th medals of his career with a silver in the 200-metre butterfly and a gold with his teammates in the 4x200-metre freestyle to pass Soviet gymnast Larisa Latynina's all-time mark.
"I've put my mind to doing something that nobody had ever done before," said Phelps, who has won 15 Olympic gold medals. "This has been an amazing ride."
Meanwhile, the Canadian team, which didn't win a medal until Day 8 of the Beijing Games, broke through early in London and continued its medal haul.
Two days after divers Emilie Heymans and Jennifer Abel gave Canada its first podium of the Games with a third-place finish in the women's three-metre synchro, teammates Roseline Filion and Meaghan Benfeito got things going Tuesday in the 10-metre synchronized event.
About 30 minutes later, Antoine Valois-Fortier surprised many by taking bronze in men's judo. And within the hour, weightlifter Christine Girard was also climbing the podium with a bronze of her own.
"It is very hard to describe how I feel," Girard said. "Four years ago in Beijing I came fourth and since then I have spent the past four years training through injuries and various changes in my life to get to this moment."
Canada sits 13th in the overall medal standings just behind Britain, which has two silver and two bronze. Canadian officials said before the Games that they were hoping for a top-12 finish overall.
Another highlight on a dramatic day for Canada was Milos Raonic's marathon 6-3, 3-6, 25-23 loss in tennis to France's Jo-Wilfried Tsonga.
The third set was the longest in Olympic history, but was of little comfort to Raonic.
"I've been sort of knocking on the door," Raonic said of his recent play. "Hopefully, next time around, I can just kick it down."
Meanwhile, the Canadian women's soccer team stormed back from a 2-0 deficit to stun Sweden 2-2 and advance to the quarter-finals, where they will take on Olympic host Great Britain on Friday.
Canada coach John Herdman relished the chance to play a game in his hometown of Newcastle against the Swedes.
"You're in your hometown, you're on your home patch, you've got your family here," Herdman said. "I wanted to make sure we got something out of this game."