Media baron Pierre Karl Peladeau has delivered at least one high-profile win for the beleaguered Parti Quebecois.
Supporters packed into a St-Jerome restaurant erupted in cheers as the controversial businessman was declared the victor in the riding north of Montreal.
The fight for the swing riding pitted Peladeau against Coalition candidate Patrice Charbonneau, Liberal candidate Armand Dubois and Vincent Lemay-Thivierge, who ran for Quebec solidaire.
The seat was left vacant after Jacques Duchesneau, well known for his anti-corruption work, decided not to run again for Francois Legault's Coalition party.
The majority owner of the Quebecor empire was considered a front-runner — one some suspect has his sights on the party leadership.
He previously vowed to serve out his term even if the PQ was demoted to Opposition status, a fate that was sealed less than an hour after the polls closed Monday.
Peladeau, a household name throughout Quebec, burst onto the political scene as the PQ's star candidate despite his hostile relationship with the labour movement, the party's traditional support base.
But as the campaign went on, some political observers suggested the candidate meant to lend credibility to the party on the economic front had instead become a liability.
The multimillionaire announced his candidacy with a fist-pumping declaration that he planned to make Quebec a country, an idea most Quebecers oppose.
The stunning move forced the PQ to address an issue it normally avoids come election time. After days musing about a post-secession Quebec, the party spent much of the campaign backpedalling as it dropped in the polls.
Peladeau himself downplayed the sovereignty issue in the following weeks, stressing he would use his business expertise to boost the province's economy.
A popular and polarizing figure, the man commonly known by his initials PKP at times eclipsed Marois, stirring speculation that he was angling for her job.
But Marois didn't hesitate to put him in his place, sometimes literally: she once gently pushed him away as he tried to approach the microphone at a news conference.
Ethics questions also dogged Peladeau, who insisted Quebecor outlets would be remain independent in their coverage.
The 52-year-old stepped down as vice-chairman of the conglomerate in order to run for office, but has steadfastly refused to sell his shares.
The company was founded by Peladeau's father and has a number of holdings in Quebec, including the tabloid newspaper Journal de Montreal, the French-language TVA television network, and Videotron.
It also owns the Sun tabloids and the Sun News Network in English Canada, a right-wing television station known for its anti-separatist stance.