SERENA Williams, 39, has withdrawn from her Yarra Valley Classic semi-final against world number one Ashleigh Barty with a right shoulder injury.
Williams had earlier beaten fellow American Danielle Collins 6-2 4-6 10-6 in the last eight in Melbourne.
Australian Barty, who won 7-5 2-6 10-4 against American Shelby Rogers, has received a walkover into the final.
Williams will be seeking a record-equalling 24th Grand Slam singles title at the Australian Open.
Williams, won her last major title at the Australian Open in 2017. She missed the 2018 competition and reached the quarter-finals in 2019, but fell in the third round last year.