'Can't believe it': Tennis world stunned by 'incredible' moment

Canada's Bianca Andreescu has left tennis fans gobsmacked during an extraordinary win over Garbine Muguruza at the Miami Open.

The eighth-seeded Canadian booked her spot in the quarter-finals with an absorbing 3-6, 6-3, 6-2 victory over the 12th-seeded Spaniard.

SENSATIONAL: Ash Barty's body-blow to Naomi Osaka in Miami heroics

'AMAZING': Tennis world erupts over 12-year-old 'switch-hitter'

'NOT BLISS': Serena Williams' candid confession about marriage

Andreescu has had a nightmare run of injuries since clinching her maiden grand slam singles title at the 2019 US Open.

The 20-year-old crashed out of the second round of this year's Australian Open, following a 16-month injury lay-off.

She then bowed out in the semi-finals of Melbourne's Phillip Island Trophy - set up for players who'd been eliminated in the first week of the Australian Open.

Andreescu suffered another injury there that kept her out of action until the Miami Open, but the Canadian showed signs she was back to her best in scintillating victory over Muguruza.

The three-set victory was perhaps best typified by a jaw-dropping point in the deciding set that even left Andreescu stunned.

Muguruza smashed what looked to be a venomous crosscourt winner deep into the Canandian's side of the court.

Throwing everything she had at the ball, Andreescu somehow managed to get a racquet on it and sent back a scarcely believable forehand winner of her own.

The incredible point left viewers - like Andreescu - in a state of disbelief.

The Canadian, who saved six of eight break points, will face unseeded Sara Sorribes Tormo of Spain in the quarter-finals on Thursday (AEDT).

"I feel like this (match) was a step closer to feeling as good as I was in 2019," Andreescu said after the match.

"And I want to just keep rolling like that and feeling really good out there and clutching tough moments.”

Canadian recaptures some of her best form

With her mom, dad and dog Coco watching from her box, Andreescu broke the former World No.1 in the first game of the third set and rolled from there, beating a player who already has a title and two runner-up showings this year.

"It's always satisfying to win in three sets, especially after dropping an opener," Andreescu said.

"Even when I’m down, I know I can find a way — most of the time, not all of the time — most of the time I can find a way to come back and do really, really well," she said. "And I keep proving that to myself.”

Andreescu broke the hard-hitting Muguruza twice in the second set after not having one break-point opportunity against her aggressive opponent in the first.

The second break, putting Andreescu up 5-3, came immediately after Muguruza got back on serve with her own break.

A volley by the Canadian touched the tape and went over before an unforced error by Muguruza finished the game, prompting a trademark "Come on" from Andreescu.

Muguruza notched the only break of the first set to take a 5-3 lead and then recorded four straight points on serve to take the opener.

“I knew she was going to come out really, really strong. And that’s what she did," Andreescu said.

"I had to re-adapt, which I did in the second set, I regrouped and I kept fighting. I changed my game plan a little bit and it worked.”

The 27-year-old Muguruza captured the 2016 French Open and 2017 Wimbledon titles.

with agencies

Click here to sign up to our newsletter for all the latest and breaking stories from Australia and around the world.