Coco Gauff's U.S. Open title defense is off to a successful start. The 20-year-old American beat Varvara Gracheva 6-2, 6-0 in just 66 minutes on Monday.

U.S. Open winner Coco Gauff will meet defending champion Aryna Sabalenka in the Australian Open semifinals after beating Marta Kostyuk 7-6, 6-7, 6-2 in an error-strewn match at Melbourne Park.

Barty is retiring only two months after winning the Australian Open, saying she wants to pursue other dreams.

On Saturday, 25-year-old Ash Barty brought Australia its first singles home win in the Open since the 1978 edition. The final game for the men's singles will be played on Sunday.

She'll be the the first Australian woman to reach the final of her home major tournament in more than four decades.

A handful of fans waving the Serbian flag greeted Djokovic at the airport.

Immigration Minister Alex Hawke said he canceled Djokovic's visa on "health and good order grounds, on the basis that it was in the public interest to do so."

The prime ministers of Australia and Serbia talked by phone about the tennis star's visa as he is seeded No. 1 in Australian Open.

The tennis star, who sought a COVID-19 vaccine exemption to play in the tournament, could face deportation again. The battle has sparked protests in the widely vaccinated country.

If he fails to have his visa cancellation overturned and gets deported, Novak Djokovic risks missing more than one Australian Open and could be barred for up to three years.

Officials in Victoria imposed a snap lockdown after several new cases of the highly contagious U.K. variant of the coronavirus were discovered.

"We will work with everyone involved to facilitate testing as quickly as possible. There will be no matches at Melbourne Park on Thursday," Australian Open officials said in a statement.