Serena Williams has withdrawn from her semi-final at the Yarra Valley Classic due to an injury to her right shoulder.

As a result, home favourite Ash Barty will progress to the final of the Australian Open warm-up event at Melbourne Park.

Williams, who is chasing an eighth Australian Open crown and an historic 24th grand slam singles success, had been in impressive form this week, demolishing Tsvetana Pironkova in straight sets.

Friday's quarter-final against American Danielle Collins proved a harder slog, as she was forced into a match tiebreak to win 6-2 4-6 10-6.

An anticipated showdown against Barty will now not come to pass, with the world number one to pursue a ninth career title against either Garbine Muguruza or Marketa Vondrousova.

"I think the rust is always there for everyone the first few matches of the season. But without a doubt, I felt better and better each match," Barty told reporters after being taken the distance by Shelby Rodgers.

"Each match has been very different, different challenges, different things I've had to overcome, which is the best thing, to be able to work through those and give myself another chance to play a little bit better the next day, focus on some new challenges for the next day."

Williams is due to face Germany's Laura Siegemund in the first round of the Australian Open on Monday.