MELBOURNE: Serena Williams admitted a calendar-year Grand Slam was “an incredible goal” but did her best to play down soaring expectations ahead of the Australian Open on Saturday.

The 15-time Grand Slam-winner has only lost twice since April and has already claimed the Brisbane International this year, showing some of the form of her life at the age of 31.

Williams also raised the stakes when she said in Brisbane that she was “absolutely” eyeing a Grand Slam of all four major titles this year, which was last achieved by Steffi Graf in 1988.

However, she remained cagey on her chances of the historic feat before opening her Grand Slam season against Romania’s Edina Gallovits-Hall next week.

“That’s an incredible goal. It hasn’t been done since the eighties,” she told reporters. “I don’t know if I can do it. Maybe someone else can. We’ll see. But it’s tough to say.”

Williams also shied away from comparing her current run to earlier stages in her career, such as when she completed the non-calendar year ‘Serena Slam’ in 2002 to 2003.

“I can’t answer that. I get asked that all the time,” she said, after being questioned about whether this is the best she has ever played.

“But I feel like I’m just in the moment right now. For this moment, I’m playing well. I really hope I can keep it up and continue to play well.”

Despite her 15 Grand Slam titles, Williams was previously known for being distracted from tennis by her ambitions in areas such as fashion and acting.

But after suffering health problems in 2010 and 2011, when she injured her foot stepping on broken glass and then suffered a pulmonary embolism, Williams appears reformed and refocused.

She admitted that she enjoyed comparisons with Andre Agassi, who played some of his best tennis in the final stages of his career.