Bianca Andreescu insists she is "not done yet" after spending years visualising the moment she would win the US Open, even writing herself fake winners' cheques.

The 19-year-old became Canada's first singles grand slam champion when she upset home favourite and Flushing Meadows great Serena Williams in Saturday's final, winning in straight sets to continue a remarkable ascent.

Andreescu won at Indian Wells and in the Rogers Cup, too, and reached a career-high number five in the WTA rankings on Monday following her New York success.

A long career at the top appears inevitable, with Andreescu still unbeaten against top-10 opponents, and she acknowledges there is now a desire to build on the US Open victory.

"I never thought it would be this hectic, but I'm not complaining," she told Good Morning America. "This is truly an amazing accomplishment but I could definitely get used to this feeling. I'm not done yet."

Williams had been bidding to equal Margaret Court's record of 24 major titles, but Andreescu's aim to triumph at Flushing Meadows was similarly long-standing.

She revealed one of her techniques had been to spend years picturing herself triumphing, determined to turn her wishes into reality.

"I've been visualising ever since I was 12 or 13 when my amazing mother introduced me to it," she said. "I find it very helpful.

"I think it's one of the most powerful tools we have, our minds. I believe that we create our reality with our minds. Ever since then, I've been picturing myself holding that trophy.

"I actually wrote myself a cheque for this tournament - back in 2015, it wasn't that much money [$3.85million in prize money] but, every year, I kept increasing it. For it to actually become a reality is just crazy."

Andreescu insists she was not interested in earning huge amounts for herself, though, instead determined to secure enough in prize money to allow her parents to travel with her on the WTA Tour.

"It definitely wasn't an easy road. I sacrificed a lot, my parents sacrificed a lot," she added.

"Just being with them to celebrate that moment was very special to me. I know they can't always travel. But I guess now they can."