The unknown who shocked Caroline Wozniacki at the ASB Classic on Thursday night said she was unaware of the score at times during the match, such was her intense focus.

Canadian qualifier Bianca Andreescu described her stunning second round 6-4 6-4 win over world No. 3 Wozniacki as a "dream come true".

The world No. 152, who had battled through four matches at the tournament before taking down the top seed in straight sets, had only previously beaten one top-50 player since turning professional three years ago.

But the 18-year-old produced one of the biggest upsets in ASB Classic history, beating the former world No. 1 and current Australian Open champion in an epic encounter.

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Andreescu said she was "in the zone" all night and it certainly appeared that way, as she played tennis well beyond her years and current level. She hit winners at will, constantly dragged Wozniacki out of position and mostly stayed strong on the big points.

Read more: Wozniacki stunned in ASB Classic bombshell

"Today I really didn't think about anything," said Andreescu. "At one point I didn't even know the score. That sounds bad but I was just in the zone today."

"I tried to stay in the present moment but at 5-4 in the second set, serving for the match, I really knew I had it then."

"I've pictured myself beating top players like this and it's just a dream come true. I know I have the level. [My confidence] has skyrocketed 20 times today. She's been No. 1 in the world, she won a grand slam."

It wasn't just the result, but how she won. Andreescu surprised the Dane with a bewitching mix of power, pace and precision and was in pole position for most of the match.

"The tactic was not to rush, to be patient, place my balls and run to everything, because she gets to everything," said the jubilant teenager. "I tried not to make the rallies too long, because she is in better shape than me."

Their backgrounds couldn't be more contrasting. Wozniacki won the Australian Open last January, while Andreescu was bumped 6-1 6-1 in the first round of qualifying in Melbourne, losing to a player ranked No. 191.

And last October, as Wozniacki competed at the glamorous WTA season ending finals in Singapore, which carries prizemoney of more than US$14 million, Andreescu was battling away at a US$60,000 tournament in Quebec.

Andreescu will be significant underdog again on Friday night against sixth seed Venus Williams, but aims to take the same fearless approach.

"I'm going to go out there, like I did today, with nothing to lose," said Andreescu. "Also being patient aggressive and have fun, that's the most important."