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The 18 year-old wild card rallied after dropping the first set to the Japanese former world number one, who had established a 3-0 lead, and held firm to cap a remarkable fortnight at home.

It was Mboko's fourth win over a Grand Slam champion in the tournament after the world number 85 defeated Sofia Kenin, Coco Gauff and Elena Rybakina en route to the final.

"These past two weeks have been insane," said Mboko, who began the year ranked number 333.

"Even getting the wild card to play here ... I was super happy to be playing in Montreal for the first time ever. I just remember feeling nervous, but really taking in the moment as much as I possibly could.

"When I won my first round, I was super happy and super content. I would have never thought that I would have made it to the final let alone win the tournament.

"I have so many emotions going through my head, I can't even express it.

Local favourite Mboko found her rhythm in the second set, breaking serve to establish a 5-2 lead as Osaka struggled with her returns, and she capitalised to level up the contest and force a decider.

The decisive moment came in the third set, when Mboko took a 3-1 lead after saving four break points in a pivotal fourth game that gave her a firm grip on the match as she went on to claim the title after two hours and four minutes of play.

"I want to thank Naomi from an incredible match," Mboko said on court earlier.

"I've always looked up to her when I was very little. It's always great to play with such an amazing player like you.

"I couldn't be more grateful," she added.

Mboko added that she was looking ahead to the U.S. Open, which begins on August 24, but also tempered expectations.

"I'll be playing it for the first time, so there's a lot of new beginnings for me," she added.

"Although I'm experiencing everything for the first time this year, I think along the way it's obviously going to be an up-and-down journey, but I just want to enjoy the process as much as possible.

"Not everything will go my way or not everything is going to be positive but I'm just really happy to be in this situation... I think it builds character."

For Osaka, who is attempting to revive her career after an inconsistent period following her return from a maternity break, defeat extended her long title drought.

"It's funny, this morning I was very grateful and I don't know why my emotions flipped so quickly," said Osaka, who last lifted a trophy at the 2021 Australian Open.

"I'm happy to have played the final. Victoria played really well. I completely forgot to congratulate her on the court, but she did really amazing."