MELBOURNE, Feb 7 — Serena Williams pulled out of the Yarra Valley Classic at Melbourne Park Friday with a right shoulder injury just days before the Australian Open. 

The 39-year-old showed no ill effects from the issue and overcame fellow American Danielle Collins 6-2, 4-6, 10-6 to set up a semi-final showdown with world number one Ashleigh Barty.

But hours later she withdrew from the tournament.   

"Serena Williams has withdrawn from the Yarra Valley Classic singles draw due to a right shoulder injury,” the WTA said on Twitter.

Williams is aiming for a record-equalling 24th Grand Slam title at the Australian Open and had been in good form so far in Melbourne.

"Look forward to seeing you back on court next week,” the Australian Open said on its official Twitter account. — AFP