Tennis phenom Bianca Andreescu won US$3.85 million when she beat Serena Williams in the women's final at the U.S. Open, but it's likely that paycheque is only the beginning of million-dollar payouts from future sponsorship deals.

Being the first Canadian Grand Slam singles champion -- at age 19, no less -- is notable, but the real story is Andreescu's meteoric rise, said Cary Kaplan, president of marketing firm Cosmos Sports & Entertainment.

"A year ago, she didn't exist as a tennis player of any consequence," he said.

The week of Sept. 10, 2018, Andreescu ranked 210th in the world for singles tennis, according to The Women's Tennis Association. This week, she's fifth.

"A month ago, if someone was calling and offering her a million dollars it would have been so important," Kaplan said.

In fact, earlier this year, Andreescu signed a sponsorship deal worth about $50,000 with Copper Branch, a plant-based eatery chain with more than 50 locations mostly across Ontario and Quebec.

But with her U.S. Open victory in hand, her financial situation allows her to take her time and determine what brands the young star wants to associate herself with.

Andrew Infantino, marketing director at Copper Branch, says the chain signed her after searching for an up-and-coming athlete from Ontario and believed a tennis player would be a good fit considering their season would be coming up in the summer.

The Copper Branch contract ends in early 2020, but the eatery hopes to extend it or sign a new one.

Until it runs out, Copper Branch plans to continue using her image on menu boards and its website, but also wants to ramp up the connection between Andreescu and the chain.

It may place lifesize cutouts of the tennis star in its stores and may add an Andreescu-themed menu item, Infantino said.

Kaplan -- who is not affiliated with Andreescu -- said the Mississauga, Ont., teen seems to embody the Canadian identity well and that's one of the things fans and brands likely love about her.

Some noted her quintessentially Canadian response to winning the final match when Andreescu apologized to the stadium crowd for beating Williams.

Kaplan said she will likely consider what brands best represent her image, adding Tim Hortons and Canadian Tire spring to mind as natural fits. Canada's major grocers and even some of the country's banks may vie for a piece of Andreescu, he said.

In some categories, Andreescu won't have the option to choose a homegrown brand, he said, and will affiliate with an international brand.

Still, Kaplan hopes she maintains relationships with her initial sponsors following her rise to fame and grandfathers in companies like Copper Branch, which endorsed her at the beginning.

Copper Branch, naturally, echoed that sentiment.

Infantino is sure Andreescu will ask for more money at the renegotiating table and he's not certain if the company will be able to afford her going forward.

"But we're also hoping that since we were one of the first, potentially we could get maybe an offer that's similar to what we have," he said.

"But I guess that we'll have to see."