Serena Williams is not taking any chances in the leadup to her defense of the Australian Open title next month.

The No 7-ranked Williams had a hitting session in Perth on Sunday and is expected to play in the United States’ second round-robin match at the Hopman Cup on Monday after missing the opening match because of illness.

“I just had the stomach flu. I was really sick and that’s not very fun to have. But I’m good ... I have recovered really fast,” Williams explained of her absence from Saturday’s 2-1 US win over India.

Meghann Shaughnessy substituted for Williams and won her singles match over Sania Mirza before Mardy Fish secured the opening contest in the mixed teams competition for the United States by winning his singles match.Williams is set to replace Shaughnessy for Monday’s match against the Czech Republic. “I was so glad when I heard that she won and Mardy won yesterday. I was really excited. I owe her a big thank-you.”

Williams had a terrible build-up to the last Australian Open, struggling in a lead up tournament in Hobart and going into the first major of the season unseeded and with a No 81 ranking. But she beat six seeded players en route to the Melbourne title.