Venus Williams' participation in the Australian Open is in doubt after the former world No. 1 withdrew from the ASB Classic in Auckland because of health issues.

19624 - Venus a doubt for Australian Open

The seven-time grand slam champion has endured a season to forget, slipping outside of the world's top 100 after a series of injury and health problems which restricted her to just four tournaments in 2011. Williams was forced to pull out of the US Open with an autoimmune disease in September.

She made a successful return to the court as she defeated sister Serena in an exhibition match in Colombia last month, but the 31-year-old has pulled out of the event in New Zealand ahead of the first major of the year as she continues to battle the effects of the incurable Sjogren's syndrome.

"We are disappointed to have lost a player of her calibre," tournament director Richard Palmer said. "While withdrawals of this nature are part and parcel of sport, we sincerely feel for the fans who will also be disappointed by the news of Venus' withdrawal."

"Sjogren's is something you live with your whole life," Venus said earlier this year. "The good news is now I know what's happening after spending years not knowing. I feel like I can get better and move on."