MELBOURNE -- Bianca Andreescu said she is skipping this week's WTA warm-up event for the Australian Open to focus on her training for the Grand Slam.

The 20-year-old has not played on tour since the 2019 WTA Finals in Shenzhen where she retired with a left knee injury.

Andreescu, the 2019 U.S. Open winner, was one of 72 players confined to their hotel rooms for two weeks in Melbourne after passengers on three charter flights taking them to Australia tested positive for the novel coronavirus.

The Grampians Trophy, a new women's competition set up to help those players prepare for the Feb. 8-21 Grand Slam, is due to start from Wednesday.

"Following the last two weeks in quarantine, it feels so good to finally be back on the court," Andreescu said in a statement.

"After discussing it with my team, we have decided to focus this week on training for the Australian Open and miss the Grampians."