The 37-year-old American, whose 23rd major win came in Melbourne when she was pregnant two years ago, won 6-0 6-2 in 49 minutes on Rod Laver Arena.

Williams holds the most Open Era singles titles, but is looking to equal Margaret Court's all-time record of 24.

"I have so many good memories of the last time I was here," said Williams.

"It was literally the best win of my career, so it's just good to get back. I'm glad that I was able to come out and do what I needed to do.

"The last time I was here I was pregnant and playing at the same time, so it's kind of weird walking back on by myself this time."

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Williams, the 16th seed, took the first set in 18 minutes against Germany's Maria and fired 22 winners during her opening match.

The seven-time Australian Open winner, who will face Canada's Eugenie Bouchard next, wore compression stockings and said she is "definitely still concerned" about the dangers of deep vein thrombosis.

"I have had some issues, and they're not done," said Williams, who experienced potentially life-threatening blood clots after giving birth to daughter Alexis Olympia.

"It's just something I have to do for pretty much probably the rest of my career, we'll see. But I'm always at the doctor.

"With DVTs, it's very scary. I know a lot of people - they're very common - have them. Especially for me, it's incredibly frightening.

"I lay on the side of precaution as opposed to not."