Serena Williams is confident a shoulder problem will not affect her Australian Open chances.

The 23-time grand slam singles champion withdrew citing the shoulder issue after reaching the semi-finals of the Yarra Valley Classic warm-up event.

Williams said: “I feel pretty good. I’ve gotten a lot of treatment already on my shoulder. But I’m super confident it’s going to be great. I’m feeling very confident, I think is a better word, and getting ready for hopefully the next two weeks.”

Top players do not normally play tournaments the week before a grand slam and Naomi Osaka, Victoria Azarenka and Stan Wawrinka all joined Williams in withdrawing from warm-up events.

There was not too much alarm over Williams’ decision, therefore, although she insisted the timing was not the most important factor.

The 39-year-old said: “I didn’t really think about that so much. I was just thinking about more or less how I was feeling. I think at my age, my career, I really just try to go on how I’m feeling physically and not put myself in a bad position in general for my health.”

It is now four years since Williams, who faces Germany’s Laura Siegemund in the first round on Monday, won the most recent of her slam titles while in the early stages of pregnancy with daughter Olympia.