Toronto's Alex Bruce and Michele Li thought they were done at the London Games after losing all three of their matches in the round robin.
However, two of those defeats came against teams that were disqualified Wednesday for losing on purpose to set up a more advantageous path through the medal round.
Bruce and Li, known on the badminton tour as Bruce Li, were re-entered in the tournament and went on to win their quarter-final match 21-9, 18-21, 21-18 over Leanne Choo and Renuga Veeran of Australia.
"We could never match a chance like that," Li said of being allowed back in the draw.
Bruce and Li had only 90 minutes to prepare for their unexpected quarter-final. Coach Ram Nayyar tried to keep the girls calm by reminding them that they were deserving of the opportunity.
"These circumstances are out of our control," said Nayyar. "Now with this win it affirms their play and their partnership."
Added Li: "We tried to stay calm. What was important was to not focus on what got us here."
The back-and-forth match lasted 55 minutes.
Canada has never made the semifinals in Olympic badminton let along captured a medal.
Earlier in the day, a discipline hearing was held prior to eight players from China, South Korea and Indonesia being expelled for trying to lose matches on purpose.
Bruce and Li sat patiently at their hotel while a decision was being rendered.
Now they're moving on to Thursday's semifinals, where they'll face the Japanese team of Mizuki Fujii and Reika Kakiiwa. After that, they're assured of a place in one of Saturday's medal matches — a position they never dreamed they'd be in.
"We wanted to go out here and put everything on the table, seize the moment and relive the Olympic experience again," said Bruce.
Li was in the arena on Tuesday when her rivals played to lose and were booed mercilessly by the crowd.
"I was thinking, 'Oh no,'" Li said. "I felt really bad for the audience, it sucks.
"It's good they took action (against the teams). It's not right that we get to play again and it's not wrong. But a chance opened up for us and it's a miracle."
Kamilla Rytter Juhl and Danish partner Christinna Pedersen were the spark to the scandal that has humiliated the sport.
Their surprise win over second-seeded Chinese pair Tian Qing and Zhao Yunlei on Tuesday upended the expected quarter-finals lineup and caused the expelled teams to try to lose.
Juhl agreed with the disqualifications but also blamed the fiasco on badminton officials for making rigging possible with a first-ever Olympic group stage. She also thought the quarter-finals should have been redrawn, as the four teams who made it on merit played each other, and the four group losers met each other.
"We know (our Tuesday win over China) is the reason why all this happened," Pedersen said. "When we said goodnight last night we were smiling, we had no idea we'd start this circus in the badminton world."
An emotional Juhl added, "I'm not happy with all that's going on right now. I hope Russia and Canada and the two other couples will come and give us thanks because Russia and Canada will have a medal, and I would like to have it myself.
"They got free quarter-finals. It's a shame, too, that China or Taiwan, one of the best four couples, will go out."
Taiwan ended up the losers, as Tian and Zhao beat them to keep alive China's streak of winning every Olympic women's doubles gold.
Asked about the expulsion of world champion teammates Wang Xiaoli and Yu Yang, Zhao said, "We didn't know anything about the controversy because we were concentrating on our practising."
Tian and Zhao will meet Valeria Sorokina and Nina Vislova for a place in the final after the Russians routed South Africa in 20 minutes.
Sorokina said they were shocked to be called back to Wembley Arena, and she and Vislova, the 2010 European champions, said the scandal was the fault of the organizers. They also didn't believe any medal would be devalued by the controversy.
"We don't think it would spoil it," Sorokina said, "we think it's our destiny."
— With files from The Associated Press