Bianca Andreescu staged a dramatic comeback Sunday to topple Garbine Muguruza in a battle of former Grand Slam champions on day one of the Adelaide International

Canada's former US Open champion Bianca Andreescu said on Monday she will not take part in next month's Australian Open as she recovers from two seasons disrupted by the Covid-19 pandemic.

During her Miami Open match against Garbine Muguruza, Bianca Andreescu stretched full-length and sliced a forehand winner, shocking not just her opponent but even herself.

Australian Open 2021: Bianca Andreescu made a winning return after a 15-month injury layoff by beating Romanian Mihaela Buzarnescu 6-2, 4-6, 6-3.

Bianca Andreescu, 20, was set to make her comeback as top seed in the Grampians Trophy at Melbourne Park starting Wednesday, but pulled out as a precautionary measure.

Sylvain Bruneau, the coach of 2019 US Open champion Bianca Andreescu, said on Saturday he tested positive for COVID-19 after arriving for the Australian Open.

Serena Willams will be looking to win her 24th Grand Slam title at the US Open this year.

The US Open will lack both reigning champions in Rafael Nadal and Canada's Bianca Andreescu.

Bianca Andreescu was billed as the top-seed in Auckland WTA Classic but she has been forced out by "ongoing knee issues", tournament organisers said.

WTA Finals: Simona Halep moved on top of Purple Group alongside defending champion Elina Svitolina who earlier beat No.2 seed Karolina Pliskova.