The three-time world champion will likely find out Friday if she's earned a spot in the London Olympics.
Her chances depend on the result of Friday's world championship semifinal bout between Sweden's Anna Rosalie Laurell and Elena Vystropova of Azerbaijan. A victory by Laurell and the Canadian should book her ticket to London in the 75-kilogram category.
Laurell upset Spencer in the opening bout at the world championships on Monday, leaving Spencer to rely on receiving a wild card berth for London, where women's boxing will make its Olympic debut.
There are two Olympic berths for boxers from the Americas. There could also be an additional berth awarded by an IOC committee.
No boxers from the Americas advanced to the round of 16, creating a five-way tie for the wild card spots.
So the further Laurell — Spencer's opening-round opponent — goes in the tournament, the better chance the Canadian has of earning a spot.
"It depends on the other girls also," said Boxing Canada's executive director Robert Crete. "There are three people left right now. As they move up, it's getting tougher and tougher, we anticipate Anna Laurell to move up, so essentially the odds of Mary moving on are quite good."
Both Laurell and Vystropova knocked off boxers from the Americas in the opening round. American Claressa Shields was ousted in the opening round by Savannah Marshall of Britain, who also remains in contention in the tournament.
Spencer, 27, was born in Wiarton, Ont., and grew up in Windsor. The five-foot-11 fighter captured gold at the Pan American Games last fall in Mexico and carried the Canadian flag at the closing ceremonies.
Spencer's absence would be a big blow to the Canadian Olympic team. She's considered one of Canada's top hopes for a medal in London, and is a rising star on the squad. In addition to being the new face of CoverGirl, Spencer is featured prominently in a new ad campaign from the Canadian Olympic Committee.